i have an 1990 1400B JCB backhoe 4x4 with extend a dig. The backhoe will run strong for approx 15 mins then tires will barely moved then stop-that happens in forward and back. If you turn the hoe off and crank it up within a few seconds it will run strong for 3-5 Mins then repeat above scenerio. Any suggestions i am going crazy. I changed the trans oil and filter even ran diesel fuel for 3 mins in trans to clean out shuttle valves-NO CHANGE please help