Yamaha DTXpress/DTXplorer/DTXtreme

Hello DTXheads,

I bought a second hand DTXpress 2 a few months ago and now have a 
problem with the kick pad. Between strokes, I lean my pedals hard 
into the kick pad- as I pull them back, the kick sample is triggered 
again. 
As I am unwilling to compromise my technique, I would be most 
interested to know how to avoid these unwanted notes firing off. Is 
it simply a matter of increasing the thresh hold? How? I don't have a 
manual.
Thanks

Max