Chainsaw Repair

Can't Pull The Starter Rope!
For the love of God, I cannot pull the starter rope on my Stihl MS271. It is not completely frozen, but it is "extremely" difficult and moves ever so slightly and in a jerky fashion. It feels/acts similarly to when starting a bigger saw without pushing in the decompression/pressure relief valve. When I remove the spark plug, I can easily and smoothly pull the starter rope, but as soon as I place my thumb over the spark plug opening I'm right back to the problem... serious compression and the inability to pull the starter rope.

The saw is coming up on two-years old and it has seen moderate use. The saw has never been abused or dropped, and I run non-ethanol gas (from a jobber) with the Stihl Ultra 2-cycle mix oil.  I ran the saw dry before putting it away for the winter and this problem occurred on my first pull after filling everything up to use. I searched on this forum, to see if this problem has happened to others; I found one thread that sounded similar and the cause was a faulty engine bearing. Any suggestions/help of next steps that I can do before taking into the shop would be appreciated. Cheers, Jim