Ed's comments on bearings are right on - but a conversion to ball bearings is possible - but also possibly ill advised. I guess I would say that if you can use the lathe unmodified then leave it as it is and keep going - albeit a little less quickly.
I'll repeat my PM reply to you here (and edit out your plaudit to me and my holiday reply.) Yunno - for the record.
1. When I engage my banjo for power feed. If I don't keep my hand on it and pressure the gears will slip out. I do see that there are 2 nuts that hold the banjo to the spindle body but I don't know if that's not common practice to tighten them to keep the change gears engaged. I don't know if that would cause damage if the gears "needed" to slip out.
The "banjo" would normally be fastened "tight" to the bed when set up to hold gears in a "configuration."
Normal setup for threading includes a gear choice from the "spindle" list placed on the spindle, another gear from the "screw" list place on the lead screw (of course you're driving TWO lead screws through Barnes' unique double lead screw arrangement - each with their own possibly mated gears) You then use the LARGE gear - in your case 88 teeth as the "stud gear" and locate a pivot stud on the banjo such that it - and the positioning of the banjo allows all the gears to touch through the 88 gear. You adjust everything in a fashion only to bring it all together - and tighten the two screws affixing the banjo to the BED
Barnes 4-1/2 banjo compared to a Barnes 5 banjo (radius of curved slots the primary difference)
Commonly seen is a small "handle" on the banjo to allow it to be more easily moved/adjusted - this handle is frequently found broken off. I've seen banjos also made "custom" out of plate or whatever is handy.
Compound gearing is similar - but in this case you use a pair of numbered gears according to the chart in the stud position. These are married together on a keyed sleeve and the barnes spindle position SHOULD include the possibility of two positions for the gear to be mounted there through use of a keyed collar/sleeve along with the nut. (either sleeve first - then gear, or gear first - then sleeve.) You will set it up with the lead screw gear and idler in an "inner" position and the spindle gear and its idler (part of the pair) in the "outer" location.
For ordinary turning, you simply set up any pair of the larger gears (one on spindle and one on stud) to hit against the 88 gear - which is mounted on the lead screw position - again, by moving the stud position and adjusting the banjo you should be able to make something that will drive the carriage at a VERY fine feed rate. I've done the calculating for this and you end up with like 168TPI if you use the 88 gear this way for threading.
When the lathe is usually first found - the 88 gear is usually on the lead screw as this is the position most usually used for common turning. Unfortunately this rather exposed position leaves the possibility for accident - a LOT of 88 gears have been broken in moving the lathe across an uneven floor and the legs bolts fail and it all comes crashing down.
2. Do you have any .off Dodson my Barnes 4.5 such as a manual or service guide. Or can you reccomend any thing.
Unfortunately I don't know of any Barnes specific information in print - other than what I have outlined of my own experience above. Most machinists of the Barnes era were usually tradesmen - and learned their craft through apprenticeship and learning from their mentors (not a bad system actually!)
Late in the Barnes era the trade school became the usual training ground and many educators wrote books for the use of apprentices and machinists generally. One VERY good book which describes EVERYTHING you might want to know about a lathe - and can certainly be applied even to a Barnes is Robert Smith's "Advanced Machine Work." Not so advanced, the book is a sort of general overview of how to use any machine tool, but includes about half the book on lathe work. It's available online at
http://www.opensourcemachinetools.org/archive-manuals/advanced-machine-work.pdf and from places online used like
www.abebooks.com for about $20.
Once again - and for the record - good luck with this.
Joe in NH