hello, I found this site looking for a cure for blocked grease zerks. My 6400JD burned and I replaced it with a 6420,3400hrs. Trouble is the treeept. arms are ceased up, not the rockshaft but the other three adjustable arms. I picked out some of the grease from threads and zerk holes but it is hard like cement. I'm putting deep creep in to try to soften it up . Any suggestions?