Put the power in the curves. You need it more there, and the variance shows less. You really don't likely need as many outside rail drops either. There is twice as much steel there to carry the same load as the center rail has.
Different locos will also react differently to drop placements fyi. It's about distribution vs draws etc.. Adding a drop to every piece would cure it, more drops= less varience on each section. try the curve trick first, 50 drops is overkill, no?
If the lock-on doesn't fit curves, don't knock the track out of gauge trying. Solder to the bottom of rails, or push a blade style crimp connector into the webs (pry open slightly, but you want a tight wedge to improve connection and lower resistance.... and protect from pulling out.)
Look at new track. Sure that old stuff works, but new really makes a difference, especially slow running. (plenty of amps in the power supply too)
Menards online is the bang for the buck option on track. (Availability at stores varies as it is seasonal. Leftovers are upstairs during the warm months, but you can go up too, no issues or asking to look)
Amps are your friend for slow running too, got enough? (which transformer? watts?)
Some folk swear by DC for creeping. You can change the ac to dc with a bridge rectifier, and normally for $2-$10 max. Nothing else needs doing, but you have to give up whistles/horns/bells on the track as they blow non-stop. (stationary whistle shacks and whistle billboards are the replacements) I don't see it honestly, but never compared closely or methodically. (sooner or later the BR can be of use anyhow, they can also be used to drop ac or dc volts 1.5v each BR used. BR is just 4 Diodes in one package. Oversized wont hurt a small item either).
