I've rebuilt 7 cylinders since acquiring my tractor and some implements over the past few years. Between YouTube and a local hydraulic shop, I've had pretty good luck. Until now.
I have a #74 front plow. There are various configurations of this device such as 74, 84, 366 and others, depending on the attaching parts, that fit different models of tractors. One part they all seem to have in common is a pair of single acting cylinders for angling. These cylinders have a small hole near the end to allow air to exit/enter as the piston travels. Moisture gets into this part of the cylinder. When I rebuilt them a few years ago, I notices a small amount of pitting near the end of the tube. I cleaned it up the best I could with very fine scotch bright pad.
The plow has been unused for two years as we've not had enough snow to justify the use. I've just installed it and these cylinders are leaking again out of the holes. I suspect I should have done a better job of removing the pitting. I've ordered two rebuild kits and will be rebuilding them over the holidays. Its not severe enough to prevent them from functioning but they do drip when sitting.
I've done some more research and there's plenty of guidance about honing cylinders when rebuilding but it isn't clear how tight the tolerances need to be. I'm planning on honing them to see if I can remove the pitting.
Question - how much I can hone them? I see one video where the gentleman hones them and puts them back together without seeming to do any measuring. Another article suggest the need for tight tolerances. I suspect application matters - there might more risk with a crane application than a snow plow application.
BTW, JD wants about $725 per cylinder and the tubes alone are over $400 - ouch. Long term, I'll probably end up replacing them. I checked online and could not find comparable cylinders. There are some snow plow cylinders that are similar but not quite the same. I'm pretty sure my hydraulic shop can fabricate the tubes cheaper (maybe).