trolling motor problem's

i run a 12 volt 50 lb all terrain tm... i have a breaker on it that use to trip all the time... last year i took out the plug and just hardwired the tm wire to my wire to the battery... my last few trip's it's been so windy i have had to run it on five speed... well after running it for 7 to 10 second's continuously on five it short's out and just get's hurky jerkey? it never has tripped the circuit breaker and the wire's back by the battery don't get hot? i can run it continuously on 4 with no problem but 5 is when it act's up. checked my connection's and wiring and everything seem's to look fine... any suggestion's? thank's all!

oops may have posted this on the wrong page:( i put in on the electronics and tm page!:)