SIII 109 Filler cap gasket: is it possible to buy?

Hi.

My single line, 109", brake fluid reservoir is leaking a little bit (more humidity than driping). I'm suspecting that it's the filler cap's rubber gasket.

I was not able to find any source for it (or the original filler cap) anywhere, just the reservoir (# 90577636) which is around 100+VAT (AUUUCCHHHH).

Does anyone knows a cheaper way to get this gasket?

Regards!

Just re-read the title and noticed it's totally misleading... should be brake reservoir's filler cap... or so... sorry

I tend to make these sort of things, it helps having a lathe to make the required wad/leather type of punches.
A good sharp pair of dividers can be useful to produce things like this, try throwing a wanted add up, someone will be breaking a 109. Where are you based it helps if people can see if you are local to them for help.

I think this is the bit you're looking for:

264767 RESERVOIR CAP SEAL WASHER | shop | www.lrseries.com

Not 100% sure as there are no pics in my parts book or on LR series

HTH

Could it be this? (264767 is for the clutch M/C res.)

606404 - Seal Reservoir Cap Servo Type to 1980

Rats, just realised that 606404 is for servo.