air leek in the back chamber

one of my 186s have small air leek on the backpanel (from driver chamber). I tought its okey because sound was nice as always and i saw no problem with it, but last party i noticed back of that 186 is getting hot (too hot in my opinion). Is there a chance its caused by that small air leek? 

Even a very capable driver may have a longer term thermal limit of 400W. This may have to kick in after a couple of seconds.

But this is thermal limiting not peak - Turn down the average and allow the peak dynamic transients. In other words turn down the gain rather than the peak limiting. Difficult I know with some DJ's etc.

Depends on what sort of speaker management you have & how hard you are attempting to drive the speaker!

Specs like "1000W" power handling for a speaker needs to be taken with a (huge) cupful of salt. It depends on the parameters of the test, what signal was used, crest factors, time, etc., etc. That is, you need to look at the small print and more importantly understand them in relation to what you are pumping into the driver.

And have you ever seen a speaker coil? It may be a frivolous comparison, but just compare the cable there with, say the coil on a 1000W heater. One designed to carry a constant high current. The other bursts of current. Overdrive and it will pop.