I have a Zd28 that I purchased this year. The built in jack handle was missing when I bought it. I ordered/installed the handle and tried to lift the mower in order to access the blades for the first time. When cranking the adjuster it will move to the end of the center pin the slot but as soon as any weight is put on it nothing happens. Like the threads are stripped out. I pulled the pin on the adjuster and extended the the threaded rod and adjuster as far as I could by hand. Didn't see any terrible threads and re threaded well. Are the adjusters prone to stripping out? Any help would appreciated.