That TT is beautiful, congrats on your purchase.
Mechanically, it's very similar to my old Thorens TD124. It had markings on the bottom of the platter, a mirror so you could see it, and a light. I needed speed adjustment for sure, so I certainly understand you wanting this, I just caution you not to do anything rude to the TT, find a temporary solution, keep looking, eventually acquire the other platter.
I found, I always had to let the motor warm up, the bearing juice to ..., adjust to steady, play, and surprisingly often, when changing lp's, need to make a very slight adjustment. We are sensitive to improper speed, however, very small variations: I tried to pay attention, could I hear if it was spot on or not when approaching. The majority of the time, myself and others, we were unaware of the small variations these TT's drift in/out of. IOW, perhaps do nothing until you finally find the other platter.
Minimize potential power fluctuations with external transformer, power supply ...?