Contract pricing can kill you too on troubleshooting.
You have be real good at knowing the cause up front. If you figure in 2 hours and a trip, and it take you 6 hours you lose also.
A couple more options for T&M pricing would be:
1. Charge a 2hr minummum.(or 3)
2. Charge a higher 1st hr rate, then reduce it to standard rate. (ie, first hr at $125hr, then $75 hr thereafter.)
