As I said, in my case my NCE Power Pro DID have to have a booster to program those locos on the programming track. So your blanket statement that they weren't needed was incorrect.
For all I know, mine is the only case where that ever happened, and I'm just the lucky one. Lucky, in this case, that I could finally operate three shelf queens.
The booster has stayed there ever since. I thus have no way to know if it made any succeeding difference. Everything has programmed fine since.
Since I had three locos that suddenly worked, I was ahead on money, since that's three decoders I didn't have to replace. And there was "nothing" wrong with them.
As I said, I do not know if MY miracle cure is YOUR miracle cure.
Ed
While we're involved with the idea of re-gearing, here's a link to some of the old NWSL reference material on gears and regearing:
https://cdn.shopify.com/s/files/1/0250/4032/2669/files/Gears_1_2.pdf?263
The current NWSL Web site is a mess, but if you click the mystery-meat three little bars and then 'Old Catalog Pages' you can still find some of the old reference material.