When I was doing slot cars back in the late 60s, we sometimes rewound our motors. I used two single edge razor blades with the backs stuck into a piece of balsa. Worked well. As long as the balancer allows free, smooth movement of the object being balanced, it will work.

As for OS engines...My first engine was a Picco .45 (a mean little Italian engine with lots of power, lots of weight, and lots of compression. My second was the old model Royal (average in every way). Then I got a Webra and an OS. I've never gone back on either. They're both great engines. I've also used ST and love them, too. I've heard good reports about TT Pro and others, but for me, the OS, Webra, and ST are it.

Dr.1