Tillers

I had a broken drive chain to the wheels, opened the transmission (after moving Heaven and Earth to remove the wheel) and found only about one tube of packing grease (mostly settled in the bottom and clearly old and not very effective).  After I replaced the chain, I repacked with three tubes, also coating the shift mechanism (space perhaps 2/3 full of grease).  After reassembling I drove it 100 feet to pump the tires (all settings working except reverse).  When I went to restart it, there was no power delivery to the wheels or tines, and when I released the transmission lever  there was a temporary, unpleasant, grinding sound.  This happened every time I released the lever to disengage the transmission.  I'm sure I have broken the input pinion and/or other gears.  How much grease should it have in the transmission after I take it apart and  assess the damage and replace the parts?