[tentcamper]

Agree, adjust until they start to drag and back off 1-2 clicks.

Did you clean off the machine oil off the new drums with brake cleaner?

You need to break in the brakes. You need to go about 30 stops. Stopping very slowly from about 30 mph, taking 20 to 30 seconds to come to a stop.

Also electric brakes take about 2-3 miles to warm up and do not brake well when they are cold.

You may need to turn up your brake controller. New shoes need to wear into the drum shape. They will make very good contact with the leading and trailing edges and the center has less contact pressure until they wear in.