Hey JMJ, I've had nothing but trouble with the stock Fender 70s type tuners on my MIJ Geddy Lee. They are weak, flimsy and often causing tuning issues. Have you ever encountered such issues with yours, and if so, have you found a suitable drop in replacement? I'm sure yours would have copped a fair beating over the years.
From what I've read the Hipshot HB2s are the business construction wise but I've heard mixed information about whether or not they are an easy replacement or require filling and re-drilling.