Went to grease my Kubota BX23 last night and the zirks actually snapped off in the head of the grease gun. Only a couple threads left on the zirk. Hope I can get the broken part out without much of an issue! Some took grease and were fine but 3 of them actually snapped. I stopped greasing the rest because I needed to use the tractor and want to pick up new fittings. Has anyone else had this problem.