yep I did a head change a few months back for this same problem,cylinder 1 misfire and it was only slightly down on compression,on removing the head and valves,the uneven valve seat was clear to see,it was causing the problem
if you are near to me,I could do the job for you,a lot less than 3...
the blend flap motors will throw up a fault code if there is a problem
normally they break around the lever/gear mechanism as they are only plastic
although I had a 164 ml which had very erratic heating problems,and it turned out to be the heater motor corrupting the lin bus system
I have a set of brand new mercedes locking wheel bolts for sale,they are genuine mercedes,and are the longer type bolt and will fit clk,c class,and some slk models,maybe more,can email photos
25 quid including recorded delivery postage
an hour,I have done dozens of these,and an hour is really pushing it,but if you can nail him on an hours labour regardless of how long it takes hime,then tear his hand off,I would want at least 2-3 hours to change one,just because it is a knuckle skinning job