DCC 300 loading difficulties

Hi Ralf et al… Here’s the obligatory video which illustrates the problem… With a tape in, the mechanism will not release without my very light manual assistance - in the first instance the motor is turning, and the cover releases a tiny bit, but that’s it. Which switch should I be looking for? Many thanks…

The metal bridge (that you helped manually) latches on the left hand side into the mechanism.
See if anything is bent/broken on the left side first, then on the right side.

Did you replace the tray belt already?

Hi, tray belt is fine and nothing is broken. I have another 300 to compare it with, and it looks exactly the same, except it works. It has a separate and more complicated problem I will post today. Thank you for your time.

No, operating the tray out of the chassis, it appears that there is a very
very light friction jam causing it not to release, no malformations, twists, bends etc. A new tighter belt is all it needs?

I would start with a tighter belt. You can also use the belt from the working machine to test?