I do over 30 200Ts a year and this is one of the most common areas for an air leak. Don't use sealant, teflon tape or anything along those lines. Get yourself a NEW Stihl intake boot P/N 1129 141 2200. The old ones degrade over time do to heat, vibration and contact with fuel. Just remember to apply a little Vaseline to the inside of the retainer plate to allow it to slip over the boot easily.
While you have her apart make sure your impulse line isn't hard as a rock and the 3 AV buffers (mounts) are in good shape and not loose, torn or worn out. If you have any questions just replace them. Another area to check is the top handle itself. I've seen a lot of them with the rear mount area compromised due to cracking. When the mounts or handle start to go they put a significant load on the intake boot causing it to fail.
Do your final vacuum / pressure check when the saw is completely assembled, with the obvious exception of the clutch cover, starter or carb if you use the factory Stihl tool for the test. When the crank case is under pressure or vacuum hold the main body of the saw down and push down and lift up on the top handle to check for any loss of vacuum or pressure. This will signify an air leak in the intake area. Then pull the engine over a few times with the recoil or by spinning the crank by hand to verify the crank seals are not leaking.
The MS200Ts has been around for quite a while and have earned a little TLC thrown their way. They have proven to be one of the best purpose built saws ever. Treat them right and they'll last a long time and make you a lot of money.
As with anything the failed part is just the tip of the iceberg. A cylinder just doesn't score on its own and replacing it will usually result in a same outcome. You must do a root cause analysis to determine what allowed the failure to occur. This may end up being one or multiple things all contributing to the failure.
Happy New Year,
MP5N
