Seeburg Jukeboxes from the USC1 in 1975 through the STD4 in 1977 used a contact blade. These blades can be easily damaged by reversing the mechanism mid-cycle. In earlier models, a technician could just flip the A-B switch and reverse operation or while serving it to clean.
These models incorporate a contact block that mechanically flips the “UP” blade when it hits the end of the carriage. Reversal early causes the up blade to jam and bend rather than drag as intended. To prevent this while servicing, you can shift the contact block in the middle by pressing in on one side just a little. Visually inspecting that neither contact is touching the Tormat. When it hits the end, it will shift into the proper position. The contact block has been nicknamed the frog by some service technicians.
If you do damage a contact, then you have three options. Bend it straight; this can be a challenge but sometimes a successful one. Replace just the contact; this requires drilling out the rivets and using either small bolts or new rivets to attach the new one. Lastly, you can replace the contact block assembly with new plastic and blade already attached.