The controls for these radios are very hard to source. If the only problem is the switch, you could bypass it and put a toggle switch on the case somewhere. This could be a solution until you find a replacement switch. If you pull the controls from some other GM radios of the same vintage, you may find a switch that fits. The entire switch assembly has to come apart to get at the switch.
Why do you want to change the power transformer? They are normally encased in tar inside the tin.
