FFT mast? A bypassing secondary lift cylinder can do this- and it's the cheapest repair. I suggest removing the snap ring or bolt fastening the right secondary rod to the mast, lifting mast all the way up, chain the intermediate lower cross bar to the outer channel top crossbar. Careful! Lower the carriage to the bottom of the inner channel, then let the right secondary cylinder drop all of the way down and now you are able to test/ prove or each cylinder one at a time. I don't remember if you are dealing with JIC fittings, but what you want to do is remove the supply line to the right lift cylinder and plug line. Extend mast all the way again, remove chain and test for mentioned dropping down. It will operate fine with only one secondary cylinder doing the work. Reassemble and REPEAT on the left side. This test will allow you to isolate the defective cylinder and confirm needed repair. We do this process often. Again, be careful. YOUR SAFETY IS NOT MY RESPONSIBILITY