I had the same issue.
If it is very minor change in slope, try tightening or shortening the pulley belt on the side that is slower to rise. It might take several times of experimenting to see if you can get the exact same travel time.
If it is a lot of change in slope, you probably will...
I'll need to change my account info to reflect my location. Sorry, I'm not to active on this forum just was trying to broaden the sale ad scope.
Sale pending, deposit received.
Very RARE mechanical skill game made in 1984.
Some say only a few hundred in existence as the manufacturer warehouse had burned down (how ironic right?).
Working 100%. Free play button added.
Clean, CPO slight crack on bends.
Display has a few lines out.
Original manual. Willing to ship, Buyer...