Electric brakes are generally not recommended for boat trailers. If your lights go out from being dunked all the time that is one thing. Brakes? not a good idea. Plus your vehicle needs to be set up for it. Electrics need a 20A circuit at least and a then you need the controller in the cab. I vote for fixing the surge brakes. They are not complicated systems. For the same reason electric brakes are not recommend for water, hydraulic brakes can fall victim from being submerged frequently. Drum or disk can get corroded and not move freely. I agree with the suggestion to do the parking lot low speed test with an helper but you can test surge brakes with a big screw driver and jack stands. Start with the basics and work up. If you can?t remember the last time the brake fluid was replaced, yes replaced. Do it. It takes less than an hour and about $10 of brake fluid. Get all that milky white water absorbed fluid out. Get all the air out. Then get a buddy to push on the tongue while you check out the operation of each wheel. Lube, clean, replace whatever is not moving freely. Only after the hubs/disk/drums check out move to the master cylinder.
