Wow, thanks everyone for all the responses!
i suppose that was why they put in a filter in the first place....
how much did the oil cost?
how much will a new set of bearings cost?
My thought exactly... about $50 of oil vs... well, I'm not sure, but at my place of work it would be hard to justify working on the gearbox/spindle bearings...
I ended up draining the oil and re-filling with new. I did not do a kerosene flush, which I regret--the bottom of the gearbox is uneven (from the casting) and so draining the oil did not carry with it much in the way of "sediment" on the bottom of the gearbox, though it hopefully took anything with it that was suspended in the oil.
GM has done testing that showed the abrasive grit left by these pads is not captured by the filters in use on car engines and won’t warranty repairs where this occurs.
This exact issue is what had me worried.
I don’t know what the filter performance differences are between your filter and the filters commonly used on their engines.
The truly disappointing (and mildly disturbing) thing is that the "filter," as I discovered only after taking it out of the machine (as this was not described in the manual) was nothing more than a rectangular piece of brass mesh, about 2x3", covering the inlet. No paper element to speak of; nothing actually serviceable. The "aperture size" of the mesh was maybe ~0.030" +/- 0.010? There were bits of string (???) that the filter had prevented from entering the oil pump, but it isn't stopping any abrasive particles.
Another thought would be to install a better filter on the machine. And change it several times in the near future and regularly after that.
If I had time, I would like to modify the cover plate to permit use of a car engine style oil filter. The cover plate is not just a cover; the oil pickup tube is attached to the cover plate, and the cover plate contains a passage which directs oil to the inlet side of the oil pump. So, a new cover plate could be fashioned which passes the oil through a screw-on filter before it enters the oil pump. Aside from time, though, I'm not sure how much vacuum would be required from the oil pump to be able to pull oil through the filter--i.e., I don't know if the pump is "strong" enough to do this. We also only have manual machines, so it'd take a fair amount of time to make a relatively complicated part like this (more time than I can afford).
That grit is going to settle in the oil reservoir so most of it will not be in the oil. So, in any case, do clean out the oil reservoir well. That may be a real pain to do and you may not get it all.
Reaching in through the cover plate, I wiped down everywhere I could reach with clean rags, until I couldn't see any more deposits on the rags. The first many times that I wiped removed some fine black residue. The interior of the gearbox was painted red, and there was so much black in places that I had thought on first glance that the paint was worn through to the cast iron, but no, the red was still there, just hiding. There was also a fair amount of fine metal shavings, hopefully just from grinding gears (not shifting fully before starting up) and not the sign of e.g., bearing failure. (I did not run the machine between removing the cover plate and draining/re-filling with oil.)
If I had more time, I would have removed the top cover of the gearbox and tried to reach down between the various shafts to reach areas I couldn't get to from the access cover, but I don't honestly think I would have been able to do much more.
PS: Scotch-Brite comes in at least eight different grits. You should know what grit yours is before selecting a filter for it.
What color Scotch Brite pad did you use? Maroon has aluminium oxide, finer grits have silicon carbide.
I was dimly aware of this. The scotch-brite pad that I used was of the green colored variety. I'm not honestly certain what is in this kind; I've read conflicting reports. I assumed aluminum oxide, but every table that I've found which indicates composition does not list the green kind. I think the green kind might be something utterly benign for household use, so maybe I had little to worry about.
Go ahead and drain the oil into three 1 gallon milk jugs. Then wait and see what settles to the bottom. Use a funnel with filter and swap the oil from jug to jug. Filter paper can be taken from a pleated water filter. I smallest particle size filter I can easily get is 5 micron. The next sizes up are something like 30, 50.
I wish I read your comment sooner--I've already disposed of the "old" oil.
It's an import so don't worry about it. I have known people who would filter the oil with a funnel and a old sock and call it done.
I'm trying to keep the fact that it's an import in mind to help prevent losing too much sleep over this. It seems to have relatively few hours on it--the ways seem to have little wear and most everything is pretty "tight," despite not having been well taken care of--I changed the oil because it had been allowed to become incredibly low in every reservoir. (About half the capacity in the main gearbox and 1/4 of what it was supposed to be in the carriage. Even less in the gearbox for the leadscrew.)
I use a solvent on RTV,usually petrol shrivels it ,if not,then try acetone......the stuff usually forms a loose mass in a few seconds,and rubs off
I have yet to try acetone for removing gaskets. I tried CRC Brakleen sprayed on a rag and found that it didn't touch it. I'll try this in the future.
....Anyway,with these zero pressure closure gaskets,there is no need to do more than slather on more rtv,and reinstall the plate.and yes Ive heard all the rtv stories....and even seen a Cat 12 grader motor with so much beads in the sump it blocked the oil pump screen......fortunately the scavenge ,so it didnt do any damage......but the pop rivets they used as pins in the clutch fell out and locked up the oil pump,shearing the key in the big scavenge pump gear.
I made a new paper gasket and put it on dry, figuring the RTV wasn't necessary because the cover plate sits above the oil level (as long as it's not overfilled), and the oil pump inlet has an o-ring for redundancy, so the paper gasket really just is there to stop leaks if either the o-ring fails (not likely) or the gearbox is overfilled.
In hindsight, probably the dumbest thing I did then was try to clean the gasket surface to bare metal--the paper gasket on top of a thin layer of old RTV probably would have been fine in this case. (D'oh!!)
Anyway, thanks again for all the responses. I definitely learned a few lessons from this that I won't forget in the future...
