"My drivability techs earn $80-100,000 per year on their hourly flat rate & get no "cut" to hang new parts..."

At that income level they need no "cut." You may be proud of that income level, but you should be ashamed by it. These people are working a 40-50 hour week but making an extraordinary income -- it's "flat rate" at its worst.

In fact, throwing parts at a problem (even if the tech gets no direct "cut") is an indirect way of getting a "cut." Rather than spend valuable time diagnosing down to the specific part, they slap in several likely suspects, solve the problem 10 minutes faster (don't forget -- the customer still pays flat rate for the repair regardless of actual time required) but at a higher parts cost. The tech has earned from the part because he/she can move to the next lucrative "flat rate" assignment that much sooner.

Tell me, Kevin, would ANY of your techs resolder an OD or fuel pump relay to save a customer $30-50? It takes about 10 minutes to resolder, and produces a better-than-new relay. It takes about 30 seconds to install a new relay. Would your dealership tolerate a mechanic that opened and repaired power window switch in order to save the customer money?

Don't bother -- I already know the answer.