Yamaha DTXpress/DTXplorer/DTXtreme

Hi everybody,

I just bought a second hand dtxpress 1. Now I have a bit of a problem 
with the trigger button: in the manual it says you have to press it 
twice to enter the gain and minvel mode. This doesn't work properly, 
mostly I have to press the button several times, and even then it 
doesn't work always. The same problem I have with the voice button, 
although it is a bit more reliable. 

Is this a common "disease" with the dtxpress? And can I do something 
about it, or do I have to send it to the Yamaha service department (I 
hope not, this undoubtedly will cost me a lot of money)?

Thanks in advance,

Anko de Hoop