Neil writes...
"As you may recall, in our last episode, the button shot out of my handbrake and bounced off the dashboard. Jeff Carpenter was kind enough to supply a spare handle assembly, but this was not the fix.
Behind the black button was a plastic washer that holds the assembly into the handle. Apparently, over time, the edges break off until it is too small to hold any longer and boiinnggg!
The fix is 07 11 9 931 684 Washer, about 35 cents at your BMW dealer. It is now a metal washer.
Disengage the handbrake. Unscrew the black handbrake knob, (this can be a job by itself) pull the knob and washer out (Mind the big spring!). Replace the crummy plastic washer with the nice metal washer and jam everything back into the handle and screw the knob back on. No need to remove the handle assembly or fool with the brake cables (Thankfully!). "