Factory tow brake’s gain is at 10

[Campingnownthen]

So our 2016 Silverado 2500 HD Durmax has factory tow brakes. When I set it on 10, you can barely feel the trailer brakes engage. I think they should be locking up at this point. We are towing a brand new 5th wheel but this was also happening after taking our 2014 5th wheel out several times. I’m thinking it is a truck issue but not sure if there are things I can check first before taking it to the dealer or if this is can only be fixed by a mechanic. Not sure what other info you might need that would be helpful but any info would be greatly appreciated!

[wingnut60]

One thing you can do is hitch up as set to tow. Pull the e-brake pin and see if the brakes lock. If they don't, that is the first problem to solve. Pulling the pin sets the full battery amperage to the brakes--should not be able to move the trailer. After checking this, replace the pin soon as possible, not good to leave that amperage on those small wires.
There are very few places that I have known who could get these type problems solved--GM dealer will say its the trailer; RV shop will say its the controller; and you still don't have good brakes.
Does the new trailer have disc brakes?
I had a friend with a '15 GMC 3500 who never could get the brakes to apply correctly to his HitchHiker. Replaced the controller twice by GM, still no good. Before he got it fixed, traded for a MH.