While Rob should really answer this, I will give it my best shot. I believe a major repair service is the kind of repair where all or most of the parts are replaced....or the
mod itself needs physical repairs to the body. And a minor repair would be for a more simple fix like a shorted mod with little to no damage. I'm sure it all depends on what kind of damage is involved too. Once Rob gets up, I'm sure he'll address this more accurately than I can.
If you are comfortable doing your own repairs, you can order parts from Rob.