Yamaha DTXpress/DTXplorer/DTXtreme

hi guys,has anyone ever noticed their cymbals 'cutting short'.i have 
my decay set about -8 for cymbals so i get the natural ringing on 
effect of a real cymbal,however at times when playing i will hit the 
crash and it will not play for the full length of sound.its almost 
like it is 'self choking'.also my snare continues to frustrate.i use 
my kit for live work on a weekly basis and quite often it will not 
trigger which doesnt go down well ,and it plain sucks when im in the 
middle of single stroke roll and it cuts out.The funny thing is that 
it doesnt occur at home when practising.it only happens in a gig 
situ,which i can only put down to prolonged playing over a 4 hour gig 
instead of sporadic playing at home.could it be to do with the 'self 
rejec' etc.i havent played around with that much as im not sure what 
to do .is there a setting that suits particular pads.i.e snare or 
kick.i would be interested to know what other users have found 
regarding this subject.i have sent my snare away to get checked out 
and no fault was found ,although,they did supply a new one to use 
while they looked at mine,and it does the same thing.!if anyone has 
had similar problems and found a cure i would love to know the 
answer........AND if possible could you let me know what 'self rejec' 
and 'rejec' settings work best for you all particularly in live 
settings ,where stage vibration etc ,come in to play,thanks to 
all,antman