I have a 99 Legacy Outback. 180K. A year ago I had a mechanic of good reputation check this car out before purchase. I got a green light given I would be willing to pay for several repairs totalling $800. He changed the timing belt, amongst several other things such as changing some oil seals, water pump, etc. A month ago, while at DEQ testing, I learned I have a misfire on cyl 1 (check engine light on). Took to mechanic of good reputation. He confirmed misfire on 1. Changed plug, reset light; 12 hrs later, light came back on. Authorized mech to change all plugs & wires, plus replace cyl cover gasket. While doing this work, he says he spots timing belt that has skipped a notch. Resets belt. Test drives car 3x he says. I pay $340 and I'm happy to have car back. I drive away. 10 feet out on the road, engine noise, engine stops. Push it back into shop. Next day, he does the analysis, says timing belt skipped 3 notches. Valve damage. $640 more to fix. He says there must be seizing between journal bearing & cam. He says he'll be worried if no evidence of seizing, like scoring. A few days later I call to check on status of the repair; he says they don't know for sure what caused the skip, but they replaced the head and the belt. He says he doesn't trust my cylinder head. My question; what could go wrong with installing the timing belt? Could there be seizing/freezing in the head that is undetectable? I want to be fair, but I need an explanation if I'm going to pay $640 more.