The gear on the right is the main drive and the one on the left is the turntable drive, so to make the turntable go at 78 rpm instead of 45 rpm that left gear needs changing. Unfortunately in order to do that you need to get the pin out of the righthand gear and it has decided that it is definitely not going to move for anyone. I have had to take it to an engineering company who can get the pin out without damaging the gears or the casting (I hope!).
I have also been putting together a Rock-Ola Tempo I and servicing the various parts as I go. The selector drum needed taking apart, then each pin needs to be cleaned individually and the whole thing put back together and thoroughly testing. It can take about 8 hours and even more if one selection wont work and it all needs taking apart again.
The Tempo I is on hold as the amplifier decided to go into nuclear meltdown and had to go away for repair.