Sony EV-C100 reel issue?
 

This deck was cleaned including the mode switch. Brand new tape loads well but will shut down. It appears to loose reel tension on the left side.eject works fine. I added a video. Any thoughts, Otherwise its pretty clean.

I'm not familiar with that deck but I'd check the small braking pads are all intact and pressing against the reel tables as per normal. Also that in Play mode, there is take up tension and supply reel back tensioning. The tape should never form a loose loop.