[8D]Sounds like the Belt Drive Pully.
You do not need to strip down the frame, the plastic frame has plenty of flex to do it the way described below.
First is it bent or damaged in any way? If not leave it alone!
If it ain't broke don't fix it.
If it is damaged here are the replacement instructions for a stock plastic frame:

1. Remove the tail boom. Leave the tail gear box and belt intact on/in the boom.

2. Remove the servo that is directly above the belt drive pully.

3. Remove the 4 screws that hold the tail boom mount together.

4. Remove the 4 screws that hold the belt drive pully bearings in place in the frame.

5. At this point you should be able to gently spread the rear of the frame and remove the pully assembly with the bearings on it intact.

6. You will need to remove the C-clip on the top of the belt drive gear to remove the belt drive gear to get the upper bearing off.

7 Reverse the process to put it all back together.

Hope this helped.

R[8D]N Sr