sounds like the auto return mechanisms underneath the table are out of sequence, or something may have broken or seized.
There is a Service Manual for the PL-5 in the vinyl engine library. These service manuals usually have a section describing how the auto functions work and what position each of the components should be in. Have a look at it and see if you can find the problem. You will need to go in underneath both the platter and the box.
Make sure your turntable is not plugged into power when you are inspecting underneath.