If you have not got a manual for this jukebox Isuggest that you purchase one because you wll not be able to check all the adjustments on the mechanism wihout one, basically the adjustments on the 1200 mechanism are basically the same as the 1100 mechanisms that were in operation until the last 1100 jukebox the 1976 Rowe Ami R-80 rolled off the production line.
If you look at the back of the tone arm you will see a plate that has two pins that follow the tone arm cam, this plate is called the Cam Plate Assembly (part number 201-10727). Make sure that he two pins are over the tone arm cam and are both still attached to the plate, I have known one to be missing, rare but it can happen.
You will see there is a 4BA or 1/4 AF machine screw that tightenens this plate to the tone arm, if you slacken the screw then you can move the position of the tone arm in relation to the start of the record. This has to be done when the record is in the play position, so select a record, make it a B side so the gripper bow is out of the way. Once the stylus is on the record turn off the service switch itwill make the operation easier without the threat of rejection.
Slacken the screw and holding the tone against the lefthand pin of the two on the cam plate assembly move the tone above the lead in groove of the record, then tighten the screw, you might need an helping hand doing this.
Please let us know how you get on.
A word of warning regarding the Memory Unit and Selector Logic boards these contain CMOS chips and they are heighly suseptible to static discharge, unless you are familiar to safe handling techniques leve them well alone.