Have you checked the overrun mechanism in the tongue, especially the damper? Also the large bushings in the outer tube in which the inner tube slides can get dry (there are grease fittings). The inner tube can rust/corrode. And the bushings themselves (some kind of plastic) can seem to swell, causing binding.

Also the cable actuators inside their housings can rust, binding and causing the brake shoes to not release. You can remove the assemblies at both ends and then add lubricant. Spinning the cable inside the guide can help free things up, also.

If you replaced the brake shoes recently, make sure you got the identical set and that they were installed in the correct orientation so they don't "self energize" to the point where they hang up.

The Alko surge brake works well when everything is in order but there are many things that can go wrong--with disastrous results.

Chip Bearden