Caterpillar D6M (1998) Hydraulc Blade

I have recently replaced both (forward/backward tilt) cylinders on my 6-way blade recently. Last weekend I was pushing over a tree and I heard a pop from the front left cylinder and then lost push power on the blade when I push so the blade tilts backwards now when I push anything. It will go back out using the hand actuator, so the hydraulics seem to still all be working but when I push something now the blade will tilt backwards and not stay in place. The cylinder is under warranty but I don't know if it is the internal packing or is there a check valve between the hand actuator and the cylinder that is allowing backflow? Any ideas?

"Thats what you get for pushing trees out with a 6 way blade!!"

I'd be suspect of the recently replaced tilt cylinders if they were working correctly before....or maybe they weren't !!!. Whoever can troubleshoot the system is going to require the tractor and blade s/n as there are different cylinders used, some with built in cushion valves and some without.