My Rokenbok Sweeper Truck does not sweep and is generally running slow

The title says it all. The truck sat in storage for about ten years and now we want to play again. The sweeper drives nicely and seems to go as fast as before. The bed goes up and down, but it seems slow. The sweeper that picks up the balls doesn’t go at all.

I tried disassembling the truck, lots of screws and wiring running throughout, but no obvious lost connections.