Trolling motor bracket???

[atlfishguy]

I hooked my trolling motor up to a 24 volt set-up for the first time today. Went to the lake today to try it out, now when I hit the pedal on high the whole trolling motor shaft and prop comes up out of the water like its too much power, I did notice the bracket isnt locking at all when it goes down in the water. Is there a way to adjust this or something so it locks? It does lock when I pull it out of the water to its normal postion. When I turn the settings down to level 1 it does fine but I want to be able to run it on high, the whole purpose I guess. Its the original 86 johnson trolling motor that came on the boat. Thanks again guys