Help with Denon DP-47F

Promised a friend of mine to ask this forum.
He has a DP-47F on the workbench.
Problem is: It plays 45 RPM flawlessly, but when he starts 33 RPM, the platter moves in pulses and rotates a little slower than 33. Also in sync with the pulsation, the 33 indicator LED blinks. For now, he doesn´t have the manual, so if anyone has experienced this, any help is very much appreciated :)
And, PRR a service technician's nightmare.

Those Denon DP series turntables are famous for age-related issues.
Personally, even though I'm quite familier with them, having serviced them, I wouldn't want to own one.
Too much to go wrong.
As for the various issues, capacitor failures are the biggest problem, and mechanism problems due to old dried up lubrication.
In addition, depending on the issues, proper test equipment is required (mandatory) for calibration and alignment, it's not something the casual tinkerer has at his disposal.
And god forbid if you're careless and damage the delicate magnetic "speed tracking" coating laminated inside the platter rim - because if you even scratch it, it's then worthless.