the last four or five cans ive bought and used have been clogging up in the nozzle after about 1-1.5 minutes of continuous spraying, then after clearing the blockage, they only last another 15-20 second before needing to be cleaned out again!! is there any way to avoid this?? i end up with sometimes half a can that just will not come out!! what can i do?? thanks, love the product!!!!