My Permagreen Ultra had a Peerless tranny. 4 speeds(maybe only 3), and reverse. Aluminum...so the outer case is attacked by the corrosive effects of the fertilizer. I have heard they cost about $700 from Permagreen. If its only small holes--seal them up with epoxy or silicone sealer. Talk to a mower shop for a new one. And...figure out a way to prevent fertilizer from accumulating between the cooling fins of the tranny case.
The Permagreen Ultra spray pump is only about $60 at Tractor Supply company. 12 volts.