Tuning Any Old School Theoben Rapid guys on here? -- Leaking problem

One of my MFRs is leaking. This one is regulated. Thank holds air beautifully up to 2700 psi; however when it's screwed into the reg, it's leaking from the small set screw shown in the pic below.

A friend and I cranked on the tank and regulator to get them to tighten together, but it doesn't stop air from coming from this hole.

Not sure why there's even a set screw right there and why can't I loosen/tighten it to any position that won't leak air?

Anyone have an suggestions/ideas?
Thanks in advance for any help!
-Jimmy

20220614_211713.jpg
 
Wrong position for the atmospheric equalization hole....Bleed hole
The position looks like the set screw that secures the valve depressing disk....
mfrregbody2.jpg


The smaller hole that is close to the receiver is the bleed hole..
If you look in the larger hole, you should see an allen set screw..
So loosen it and you can unscrew the depressing disk...
reg-front-strip1.jpg

Underneath it is the sealing O-ring for the disk..
reg-front-strip2.jpg


So what is causing the leak from that large hole on the Reg for the MFR. It is the Bottle sealing O-ring on the depressing pin!!
MFR%20Oring.jpg


here is a hot of some of the More common O-rings used in the Rapid Airguns.....
RapidOrings_1_.jpg


HTH,
Good Luck,
Stuart
 
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