Why can't I fix lawn mowers?

It seems all my life, I been at the mercy of mechanics. All this week I have tried to get the 2 and one half acres of grass mowed. I have both a lawn tractor and a small push mower. I messed up one of the pulleys on the tractor. The mechanic repaired it with a plastic pulley. It lasted about 15 minutes before the plastic unraveled, or whatever plastic does. This morning I had to make another 25 minute drive, and hopefully he can replace the idler pulley with a metal one. On the push mower, I bent the blade on pine tree roots.
I let about 1 and one half acres have a meadow in the spring until the clovers stop blooming, or until I can take the growth no longer. It's time to mow. I have to mow it twice to get it all.