does the playfield need to come out to apply the felt?

No, you can if you want to felt the entire length of the playfield but I have found this is not necessary since if you use the thicker type felt I suggested earlier on both sides of the playfield this basically eliminates any side to side movement of the playfield itself, thus stopping any unprotected areas of the playfield from making contact with the mirror blades. Whilst I applied felt the whole length of the CV playfield since it was out of the cabinet anyway (resto job), I applied felt to approximately 3/4 of the length of the sides of my TZ doing the following with the playfield still in the cabinet:

In cabinet method:

What I did was to pull and raise the playfield to its vertical locking position resting against the backbox and then applying the felt as far back as you can reach BEYOND the edge of where the cab meets the playfield of at least a couple of cms beyond (it will be a tight fit to work it in there whilst the playfield is in situ I suggest physically pushing the playfield the few mms across to the other side of the cabinet whilst doing this for each side to give yourself a bit more room to work with).

Measure and cut the felt for both sides of the playfield the same length and apply them in the same starting positions on both sides to ensure the felt "buffer zone" is even.

Whilst it may seem like a chore, applying the felt beyond the edge of where the cabinet and playfield meet will ensure the felt will not snag or catch on the cab whilst the playfield is being slid back in from the forward locking position or lowered from the vertical locking position. it will still leave about a quarter of the back section of the playfield sides unprotected but as explained above the thicker type felt acts as a a cushion and stops any side to side movement of the playfield, and stopping any possibility of the unprotected areas rubbing against the blades.



It sounds over complex, but it should only take 10 minutes tops and will ensure that you never have to worry about scratching the panels when lifting or sliding the playfield in and out of the cab.  

PS: The felt goes on first and the blades are the last thing you install.