I was wondering if there was any quick fix for a broken spring in a Pro-Max 239A brake lever. It seems a waste to buy a new one for a broken spring.
This sort of component-level repair is rare in cycling. Generally speaking a shop would fit a new replacement brake lever and clamp. Moving sub-components around would be the realm of someone valuing a period-correct part over functionality.
I'd replace both brake levers with either new or a good quality used replacement.
Why both? So they feel the same when in use, with similar action and pivot distances.
Brakes are a critical safety component, and I'd think very carefully before twiddling internal parts around and using a generic item as a replacement.