I had a grease fitting on my 2501 I suspected wasted taking grease. I bought some 10mm zerks at TS and tried to swap it out. I got it about 1/2 way in and it came out. Now I can't get the old one in or a new one. What size zerks are on a 2501? I also want to get a 4-way zerk tool and cannot find a metric one. Do they make metric Zerk tools?