Thanks for the response SM. Problem was repaired about a week ago. I determined it was not a mast mechanical binding problem, and felt the oil was getting on top of one/ both the secondary lift cylinder pistons and the center check valve was stuck or blocked, causing the presumed oil on top of the pistons to "fluid lock" the cylinders. I ordered the kits and hauled to the shop, removed and disassembled cylinders. What we found were both piston seals blown, cracked up. However, the check valves were fine, and no debris was found in the hollow section of the tubes. This is a common failure on lots of OEM cylinders, and Cascade as well. But never with the "loading" symptoms we had on this particular machine. What I did notice was the hollow cavity on these tubes was only about 12" deep. Not the entire tube as is common. My theory is that a bigger hollow cavity would allow more oil/ air to push internal when the cylinder begins to leak- allowing a cushion of air to compress. The smaller cavity- not much ability to compress. Would love to hear some feedback. Thanks all.