Kenmore 1990s 70 Series Washer makes horrendous grinding noise during neutral drain cycle

[brd]

Just started last night.  The gearbox was replace in Jan 21, so 3.5 years old.  It runs fine through agitate cycle, then when it pauses and reverses motor direction to drain, it makes a very loud grinding noise.  

I verified that the motor is spinning freely, the pump spins freely, connector bushing and plastic pieces between motor and gearbox are good, clutch is good, tub brake mechanism is okay, tub spins, agitator shaft does not bind in tub.  

I suspect the agitator cam at the bottom of the agitator shaft inside the gearbox, but I've seen tons of links and videos for neutral drain kits, but I'm not sure that's what I need?  Also, apparently those agitator cams are no longer sold separately, only as an assembly with the whole agitator shaft.  

[brd]

Well, if anybody cares, I wasted $40 putting a neutral drain kit in.  Must be the agitator cams, but you can't buy them separately anymore?  just a whole new agitator shaft with cams attached?

I want to keep the old girl going, but I'm not sure a gearbox rebuild every 3-4 years is worth it.