Hi mate, just done a similar thing, been out of trials for 30 years (started on a TY80 like a lot of us did.)
Just bought a Beta Rev 3 250 and the seals were leaking quite heavily. I ordered some replacements, but on the off chance bought SEAL MATE and it worked a treat, got all the crap out of the seal and hey presto no leak.
Some guys passed on some good advice, buy lots of RADOX !!