Last post was almost a year ago and I am sooooo grateful I found this thread. I attempted to fix my wife's D80 following these steps and when I got to the gear it was indeed the plastic rivet that was broken. I took off the tiny screws of an old pair of sun glasses and fastened the metal brushes to the gear.
Sadly mistakes were made...
When putting the gear back on I inserted it and with my finger rotated the gear so that the arrow would be in the center of the window aligned with the other arrows... This created a problem I would not detect after a very long while... After assembling the camera, I noticed the top LCD was not showing anything and the power switch was not turning on the camera... I reopened it to check all my cable connections. After checking all the connections, I closed everything back up and when inserting the battery had a green LED light on the back turn on. Top LCD was working and I decided to take a test photo. I pressed the shutter and this caused the mirror to remain in the up position blocking the view from the viewfinder when taking pictures. However,the error was gone and the camera was cycling properly.
I reopened the camera after deciding that it was the gear. Got all the way back to the gear and... (I was tired, please excuse my fleeting intelligence) Rotated it again with my finger to align the arrows. Closed everything back up and took a picture, the mirror locked up again in the up position..... Got upset and called it a night.
On Day two I reopened the camera and got alllllll the way to the gear again and this time I pulled it out. Lowered the mirror manually THEN aligned the arrows and then inserted the gear. Closed everything back up and the top LCD had no signal and power switch had no control. Reopened checked all connections closed up. Bulb Err. Reopened checked connections again and found a green wire from the bunch the goes from the top of the camera to the left side (looking at the read display) floating freely, I looked at where the other connections are going and noticed there was a solder spot under the black wire with a + on it. I figured It broke off from there and resoldered it back on.
Now the problem I am currently facing and where assistance is required is that when I insert the battery no green LED turns on on the back side and when looking at the top LCD, as soon as I insert the battery it shows the battery being read and then I am greeted with [-E-] in the lower right corner. I have not powered up the camera because I don't trust myself in soldering that green wire to that spot.
Please help me.
Wire Picture