Turhand, I have an old grease bearing job like yours, except it's really worn. Mine is rigged for USA, 120 volts 60 Hz. Yours is probably 240 volt and 50 Hz. I used a variac for a while. The speed is set by the line frequency, but when you reduce the line voltage (below 90 v for me) you begin to lose power from the motor and the speed becomes erratic and begins to slow down. My experience was that reducing the voltage did reduce the noise and vibration from the motor somewhat, making a quieter playback (less apparent rumble). I had to be careful, because there was kind of a "null point" where the turntable would quiet down, but it would also start to slow down. Remember, on these things the eddy brake is on all the time. What you do is reduce the voltage while you are playing a record with blank grooves on it (no sound or really quiet runout grooves). Turn the bass up before you adjust voltage, and you will hear the decrease in apparent rumble. This will tell you how far is far enough. If it slows down, it's too much. For me the use of the variac was not a big deal, but I had a fairly heavy plinth. The change was subtle. For others, it might be significant. These old Garrard 301's have huge, powerful motors that do vibrate some. That's why you want a massive plinth, to eat the vibrations. Or you can use a variac. Good Luck again.