trailer brakes 'grabby' when warm and used lightly

TRy backing off the gain - mine are grabby at slow speed if the gain is too high.

Last year I had similar issues which drove me nuts. As others have pointed the wiring is usually daisy chained from one wheel to another. I removed the wiring and had a dedicated wire to each separate wheel. The braking is now much better and even.

I did notice a loose ground - so I suspect that this may have been causing some issues with the "jerky" brakes.