If you have the coil, typically on R2LC versions C07 and eariler, as well as the old LCRU and LCRX boards, you can tune them.
The method is simple, you just power up the locomotive and try a command like the horn, turn about 1/8 turn and do it again. Repeat until the horn stops working or the locomotive start powering up in conventional mode.
Mark the position.
Turn the coil the other way about 1/8 of a turn and use the horn again and mark where it stops. Center the adjustment between those two points.
You can also tune the old TMCC command base in a similar manner using a modern locomotive with a known good R2LC or R4LC.