I have an issue with the Hydraulic Ram on the 3 point linkage lift arm. The tractor is fitted with a control box for the 3 point linkage and a toggle switch that actuates the lift ram. The issue I have is after the tractor has been running for about 10 mins the ram extends fully and the toggle switch will not work. The main 3pl control still works. Has anybody seen this problem or maybe have a diagram of how these control units work..