Even though this is an older post, it may be relevant for a long time to come,
as this issue won't be going away anytime soon with all the Fluke meters out there for over 10 years, and still being manufactured..
I've had the same issue with my Fluke 289 for years,
praying the broken and crumbling silly plastic lock would hold,
which was always half turned to lock/unlock with my thumbnail carefully whilst 'meter whispering'

close up,
and not forced with a screw driver.
Otherwise once that silly part got totally disintegrated (update:yesterday) with no
(cough..r!poff priced) Fluke part available
without buying a
(cough..r!poff priced) complete back replacement,
I was planning to resort to eyesore duct tape,
and as a twofer, kill the resale value of the meter sometime in the
-very distant future- = I still like this meter

Anyways, I got to thinking and came across this post here about it, so time for some 'homework'.
For starters:
the Fluke 289, 233, and 1507 all share the same half turn lock knob arrangement. Most likely the 287 too, if any others I don't know

So for now, because the 1507 gets used less, already has an extremely tight back,
and has it's yellow holster as well to hide my duct tape handiwork,
I put (carefully sliding and nudging) its lock on to the 289
and now, no more crossed fingers or popped back for the batteries to fly everywhere,
and or the plastic back dropped/damaged/shattered.
Mini Rant:

These Fluking parts should be readily available for these EXPENSIVE meters,
and seriously folks, how is CAT 111 and CAT 4 supposed to work if the back of these meters is wonky and or pops out,
the batteries fall onto live electronics/electrics,
or during a 'meter death arc', due to poor choice of probe/selector switch combo and -idiot prodding-
it all blows out into the users face because the silly plastic lock decides to FAIL ?!!
All that aside, I will follow through with member retiredcaps link above, and hopefully score a couple of these
silly items
and restore my 1507's lock function
and future resale value Lastly, the Fluke 101 meter has the same style of half turn lock/unlock knob come battery cover latch,
but it is a smaller size,
and not compatible with the bigger bro meters, or vice versa.
Watch out for that one, and save yourself cash, disappointment or lab rage on delivery day..
If I get lucky with getting these plastic thingies, I will be back to report.
Cheers
