my shifter is shifting

[Doug Stampfer]

Had a few offs lately & found that my SLX shifter is moving on its' perch when trying to shift. I tightened it up but no go. I took it off the perch & noticed on the bottom it has a steel roundish kinda fixing plate with 2 square edges that should sit into something in the base to stop it twisting however the base doesn't have anything for it to sit in so just spins when pressure is applied.
Can anyone decipher my cryptic description & let me know if something has broken off or am I missing a part. I'll post pics soon.

 

[Gary]

Something about your perch doesn't seem quite right

 

[Doug Stampfer]

Very good Gary. That’s going straight to the dad jokes hall of fame.
Stand down everyone I’ve found the problem. There was a microscopic screw missing that locked it in place. Luckily I had a smashed laptop with one I could salvage so easy fix.
Teachable moment though for those like me that hadn’t noticed, there is a quick release to remove the brake lever off the bar - nice work!

 

[Stihldog]

Almost lost that shifter screw a few days ago. Gonna check that more often. Lock tight maybe?
But I can’t figure out the part in the second picture?

 

[Doug Stampfer]

That there be the perch. You may have been distracted by Gary’s version which it has to be said would probably be what it would look like if trek had actually designed it ?