What type of motor did you buy? I was thinking of doing a tombstone popper for next year. I was thinking of doing a grave digger and a breathing grave with the motor I posted above.
https://smile.amazon.com/gp/product/B07TFDPZP7/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 offers three motors along with attachments and cords for twenty bucks. They make 5 to 6 turns a minute which keeps the prop rotating enough to keep people's interest. In the future, all we'll have to buy are replacement motors if any of these should fail. They're definitely not strong enough for rolling graves or any other prop that uses a wiper or rotisserie motor to power the movement. But they will pop up and wiggle some of our favorite props.
Our tombstone popper is probably heavier than some which is what causes the synchronous motor to reverse the turn, but we're happy with that result even if it wears out the motor prematurely. From past postings, putting nails in place to force the reversal won't save it and possibly even helps it fail earlier, so we're just letting it do what it wants to do.