I believe I can see some other problems with your reverse unit which are going to cause a failure later on.
In picture four if you look to the left of the red wires you will see a metal tab that protrudes through the brown finger board to keep it in position. It looks like someone has removed or replaced it in the past and not secured it correctly to stop it lifting which will cause the fingers to not make contact with the drum. They need to be twisted by about 20-30 degrees to lock the board in position. You also need to make sure the boards are all the way down as you twist the tabs. Be careful!!
The finger board on the end where the yellow wires go to looks like it may be lifting away from the frame already.
Here are a couple of pictures to help. The first one shows both tabs verticle and in alignment to the main frame. This is the position they need to be in to remove and replace the boards. In your case you can twist the tabs with the wires connected, you don't need to remove them. A good pair of needle pliers is all you need.
The next one below shows the twists in the tabs to lock them in position. Sometimes they may need twisting a bit more, if they do, just do it by a small amount so that there is no movement of the board.
