Ok here's another idea:
A business needs, in order to survive, to rely on the strenghts of its worker(s) and it does so by *allowing* its workers to DO what they do best.
IF your friend is the BETTER grass-cutter AND you are the better manager (in short), then your friend should do what he does best and you should do what you do best.
Hate some your stuff, want to do some his stuff? maybe he hates some his stuff, wants to do some yours...
perhaps see if you can switch some of the tasks, have a talk...
by the way, if you're tired of being saleslady, I ain't no
[email protected]!7ch either so the easy solution is spend some MONEY on advertising (3 thousand a year should do, but since it's 2 of you, try 4 for starters and don't be afraid to send another 2k after it) - newspaper ads, yellow pages.
Once the calls come in, I don't mind giving the estimates so long it's a TON of calls so I don't gotta make the sale - Take it or leave it, I don't care. <- THAT takes the bs out of it real good.
Does it work? Hell yeah it works!
Far as the maintenance, make it better: Find ways to do it faster, make it easier: Buy a big air compressor with a tank and get some air-tools, bro you'll be like the nascar pit-stock crew working on your stuff.
spend some money, f*k it, invest it in better stuff, more business, increase production, come on, have some fun.