Thought I would pass on a recent experience on my Case 580se.. Hope it helps someone. Low hours and works fine except for a huge shudder at 1700 rpm and a reoccurring cooler leak. Local veteran told me most have such a shudder. Short story is, per some speculative comments on HEF, I removed rear motor mount bolts and replaced both back rubber mounts. I left the bolts barely threaded. After loosening the fan shroud, I carefully jacked up the front of the engine and with some rubber lubricant and determination, the front mount slid in ( without taking much else off) Tightened the engine down and ZERO shudder at all RPM! Good luck, Pilgrim22
When I seen your post I was going to tell you just replace the motor mounts. After I read it I was glad you sorted it out. I have seen many absurd responses on this subject. Glad you had the wisdom to figure it out instead of tearing half the tractor apart looking for nonexistent problems.