hatch/trunk lock problem

[Arlene '07]

Suddenly, my rear hatch won't lock unless I click the hatch-lock button on the key a few times. My '07 Mini Cooper has 28,000 miles on it and an otherwise unexceptional history. Anybody had this problem? More importantly, any ideas on its cause and how it's fixed? I'm scheduled to take it to the dealer next week, but it's a long drive and a day off from work and the friendly service guy says they've never heard of this problem, which is worrisome in itself.
Thanks in advance for advice and comment!

[bad venge]

first thing I'd try is flushing the latch assembly with a solvent then relube with some white lithium ... the hatches seem to suck up the dirt from the road and deposit in the latch assembly