Bally 831 with a cast Aluminum air cylinder

[Amechanic]

I had two Bally EM machines come in for service today. One is a JPO 809, the second is a 831 JPO.. I just wanted to share this and as if anyone has ever seen a cast aluminum air cylinder on a Bally EM? At first I thought it was painted silver until I removed it to service the seal inside. Then I realized how heavy it was, that's when it hit me that its cast aluminum.. This has to be off a much earlier model. I was hoping that OldReno or Jon might have some information on this piece. See pics.

Gary

[OldReno]

Yes, I think earlier models.  I'd run across them from time to time when doing my daily machine overhaul/rebuild at work.
Not too rare, but fairly uncommon....
There was a retrofit/addition someone came up with once, that was a small adjustable valve that you could drill and tap onto the outlet hole, that allowed you to adjust how quickly the air came out.  Allowed for additional cushioning for wear and tear on the mechanical parts during handle pull and reel kickoff.  The device didn't get a lot of notice.  Didn't seem to do a lot, but some mechanic somewhere made the thing and manufactured limited amounts I am guessing.  I do think a working rubber seal allows for longevity with wear problems, but then these machines aren't being played 24/7 anymore, so that's not much of a factor nowadays.

[Amechanic]

Thanks for the input on the air cylinder.. That Aluminum air seals still good! I just cleaned it up and put a light coat of oil and grease inside the cylinder. First cup seal I've seen that was not turning to tar..