I love how I'm always learning something new on this site. My B2910, which I got second hand, came with a block of wood in the tool box. The block has a groove on one side and some illegible writing on another side. I've always wondered what it is for. Now I know it's for the clutch. I figured out it's goes on the underside of the frame, between the frame and the rod connected to the clutch pedal. Very cool.
On the good side, if I forget it's there it will fall off when I press the pedal. On the bad side, it will fall to the ground and I'll run it over. Maybe I'll drill a hole through it to run a string or chain through so I can hang it.