Unfortunately I am not mechanically minded and for one cannot do anything better than a complete dismantling of my r/c plane's 2 stroke engine and reassembling it in a few minutes. The only other thing I had to dismantle was a M16 in field training. So I am at the mercy of the techies who charge up too many hours when you leave your car there for a few days. At one shop, I was prevented from watching the work done due to "workshop insurance cover regulations", LOL. They even charged me time for their 30 to 45minute teabreak, their lunch time and the time it took them to walk back and forth from the service area to the parts dept., waiting time to be attended and as it was a Saturday there wasn't any other idiot stupid enough to send their car there on a Saturday. My Benz's stuck centre vent is being fixed this moment by a trustworthy techie far away, but if he says it needs replacement, it needs replacement.