My searching leads me to a Leinbach notice stating they do not deal with customers but just their dealers and customers need to go to an authorized dealer for support and they recommend (Temporarily blocked due to reports of company closure)
Everything attachments does not mention Leinbach directly but look at the post hole augers they sell under their own name. Probably Leinbach products re-branded.
Everything Attachments | Skid Steer Attachments, Tractor Attachments, 3 Point Hitch Attachments, and Farm Tractor Implements.
Look over the pictures on the above link to see if you see yours. If you do email them and ask for a manual.
Do you have a specific question, type of lubricant perhaps.
There is a description of the 7200 which you likely have:
Confusion often arises in web sites because the information may be badly out of date and thus misleading.
The L7200 Leinbach Post Hole Digger is made with a tubular mast and yoke. The gearbox has tapered roller bearings, which run in lubricating oil. The gearbox control handle allows for the drilling of a perpendicular hole. The individual one piece cutting bit is replaceable. The four-position boom allows for adjustment to fit most category 1, 3 point hitch tractors. The output shaft is 2" round. The shielded PTO shaft has shear bolt protection. The gear box has a directing rod. This Leinbach Post Hole Digger is made for the full size and larger compact tractors, for use with up to 12" augers.
Dave
M7040
