David:

If yours is the Testor's McCoy 29 you might well save your time and effort. Even with 25% castor the engines didn't last very long. The only good thing was the low price.

Back in the early 60s we'd spend $10 at the LHS, walk out with a new Testor's McCoy 29 or 35, and a gallon of fuel. When the fuel was burned up the weekend was over, and so was the engine.

Next weekend? Another $10, another McCoy Redhead Stunt 29 or 35, another gallon of fuel.

Bill.