BROTHER HS70AM Tank arm real seal replacement

Need to replace my rear arm tank seal. Brother no longer services these machines. Anyone have a suggestion to what I should use?

Without the original part, it will be a BITCH!

Is it the round seal around the arm, or the stainless sliders?

Seems it's the round seal

Well, without a new part, you MIGHT be able to repair that one.

It is a flat U channel with 2 O-rings on the outside and some teflon coating on the inside.
It is then sandwiched between 2 plastic flanges.

If it isn't broken yet, then you MAY be able to carefully slide it off the arm.
Replace the O-rings and re-coat the inside with either teflon tape or some paste.

The primary cause for these to wear is that the lower arm often gets neglected and dirt builds up on it.
That dirt then wears a groove into the teflon coating.

In 20+ years I've replaced one on each of my machines.
May seem a bit challenging at first, but it surely isn't all that bad other than the fact you ain't got a whole lotta room in the back to clean shit up properly
so the bolts can be accessed and then reassembled.
The ring will easily come around the lower head, just make sure the arm is fully cleaned and then WD40 so it slides easily.

Thank you, is there recommendations or a need for lube on the lower arm?

Absolutely NOT!

It would either was-off and contaminate the water, OR will not wash-off, thereby collecting particles to abraid the moving parts.

I occasionally use some ridiculously small amounts of plane-jane Vaseline on parts ( O-rings, plane bearings, plastic part etc ) to ease assembly, but beyond
that nothing submerged is lubed.

Thanks . I'm new to wire edm. I picked up the ,brother hs70am second hand. Gonn give it a go. While I'm a seasoned machinist cnc and manual, the wire is a new deal. I thank you for your advice and this site is a priceless resource.