D-15 with problems

DJay

Hi, I bought a D-15 that was supposed to be in good condition, but as often happens, it turned out that it wasn't. I took care of the entire traverse and it started. The problem is that in the horizontal position it usually doesn't read TOC and generally doesn't play. It has no problem vertically and upside down, it plays and doesn't skip. If I start it vertically and lay it down, it can play normally, or it starts to skip after a while. Does this look like a problem with spindle motor or rather aging lens?
Thanks