I've done quite a bit to my TD125, all pretty simple and helpful. I removed the pressboard bottom; this helps remove resonances associated with the base. I installed small brass cones on the 4 corners for feet - very useful. I use TriFlow for the main bearing oil bath, seems to work very well. If you have a dustcover, don't play and record with it down, or even better, remove it completely. I replaced the rubber mat with an old Linn Sondek felt mat. Any replacement mat will be an improvement.
Regarding the SME arm, mount it solidly, use a good cable and enjoy it!
The above are all pretty cheap and help a lot.
Regarding the SME arm, mount it solidly, use a good cable and enjoy it!
The above are all pretty cheap and help a lot.