Famicom Disk System issues

[LaughingElfMan]

Hi all!
I recently replaced the belt in my FDS, which went suspiciously smoothly. I was right to be suspicious.
Now, the drive always thinks there's a disk inserted. Tries to read constantly as soon as it gets power.
Did I break something? Can you think of anything I might have done that would cause that? Thanks for any help you can offer!

[jb143]

I'm by no means an expert and have never worked on one of these, but I am familiar with electronics in general. But here's some things you can check.

There should be a switch that gets activated when a disk is inserted. It's possible that it got stuck closed somehow. Maybe when putting everything back together. If it's not noticeably stuck, then you could try to read continuity to make sure it's working correctly.

Good luck!

[FoxNtd]

This is the top of the drive, with the front of the unit facing the left side of the picture. On the very bottom of this picture you can see the disk ejection switch. The plastic housing itself has that L-shaped arm that throws a thin long black plastic lever down, which in turn closes the circuit of the brass plates to signal to the system that a disk card is inserted. You want to check what is going on here first. When there is no disk and the assembly is in empty/ejected position, that lever should be raised by itself under spring tension.

[LaughingElfMan]

The arm and switch look good. The housing raises and lowers, causing the arm to press the switch.
I actually removed the plastic housing, hoping to find an obvious problem. No luck. Would any of the other switches be able to cause the issue?
I've also noticed that the device will only work on battery power, so I suspect the voltage regulator needs replacing. That couldn't be related, could it?