Man, I gotta disagree on the standoffs part. Every time I've seen a loose bundle with standoffs on the APU harness, it just gives the wire more room to slap around in the vibration and that's where your chafing comes from anyway. The fix I was taught is a snug bundle with the right lace spacing, like every inch and a half, but not cranked down so hard it dents the insulation. Too tight is bad, but too loose on a 737 APU is asking for rub points at the clamps.

The $75 to look at it upfront is the way I've always run it, and yeah it keeps the folks who just want a free peek from wasting a whole afternoon. Had a guy last month call about his fridge, paid the fee, turned out to be a $9 relay. He was happy to pay because he knew what he was getting into. My buddy tried the free thing for about six months and ended up driving all over town for people who never booked the actual fix. Charging up front tells you who's serious right away. The tire kickers weed themselves out and you keep the ones who actually want it fixed.