Allis 7000 "very weak reverse gear"?

I have found a 7000 for sale with 20.8-34 singles , 60% not cracked, fronts better, tractor is a 6/10. The vendor says it has "a very weak reverse gear". He claims forward gears are working correctly. What could a very weak rear gear possibly mean, and what would it take to repair? My Dad bought a new 7000 in 1976 but I dont remember any trouble with any gears...Thanks in advance, Trev.

And on the brown belly models, sometimes the gearshift would actually hit the seat (if the seat was clear ahead) and not fully engage all the way causing what Bill described.

My black belly's reverse gear was pretty badly eaten up, but the countershaft and the sliding collar gears were still in good shape.  It seems that Allis used a metal that was quite a bit softer on the idler gear than the countershaft and sliding collar.  To replace the gear, you will need to take the differential cover off and the shifter tower.  Then you will need to drain the oil down in the differential (probably be best to drain it all out, because chances are you will drop the ratchet, socket, bolt, or retaining tab, or some combination of these in the bottom of the differential housing).   Then go in through the differential housing, undo a 3/8 bolt that takes a hand half as big as yours to get to (and a few universal joints and extensions) and remove the retaining tab.  Now you need to go in through the top of the shifter tower and work the reverse idler shaft back towards the differential until you can get the gear off the shaft.  Mine slid very easily, but I have heard that some are not as nice.  If it doesn't slide easily, I'm not really sure if you can hit it from the back and knock the shaft forward.  If you did this, I'd be worried about getting it slid back without having to do a rear split so you can tap it from the front.  If you buy the A&I gear, you will need to take the gear and shaft to a machine shop or if you have a lathe, you can do it yourself, and have them sized to each other for a nice slip fit (a couple thou tolerance between them).  Then you can put it all back together, making sure everything is in neutral.  When you put it together, I put some sealant around the reverse shaft between the differential and transmission housing.  It seems that this could be a place for fluid to transfer.  Basically, put a run around the shaft while it's slid out an inch or so, then push it the rest of the way in and maybe spin it back and forth a little.

Definitely don't split at the rear without taking out the transmission brake shaft and all 4 of the powershift/trans lube lines (have to take off the powershift valve body and an elbow fitting on the opposite side).  I found this out the hard way...and I own the service manual (I just started reading one section too far forward when I did my rear split...).  It's a pretty simple split after that, but you definitely don't wanna make the same mistake I made...