I have a TZR250 & an 87 RD350.
Both are leaking at the gear shift shaft.
Has anyone used this type of seal.
I have also seen them on Ebay.
https://www.amazon.com/Gear-Change-Seal-Ring-Yamaha/dp/B0BDQBKPJ9
M
ive seen people use it. the issue is actually from the support on the cover wearing and allowing the shaft to flex, not the motor. (like 99% of the time). we fixed this on matts 400 by putting a bronze bushing in the cover. done, fixed. its a band aid that kit, but it is 'ok' . not sure it it will work on the tzr.
I did use that on my 400, Milan. Bought from some dude in the UK a few years ago.
Still quite happy with the result.
I would consider using Mark's solution along with it if I didn't have plenty of other issues to work on.
No leak here, but it eliminated the wiggling in the shaft that you don't necessarily notice on a 7500 mile bike.