It wouldn't be that difficult to make a counterweight- - - - -just do a little tinkering with the offset to give it the right amount of leverage. I'd use something like a piece of 3/4" steel square stock with a hole drilled in one end and a slot for a pinch bolt to clamp it to the shaft. Most of the resto-ripoff sites sell the spring.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!