2N4401 are just a signal transistor - generic replacements are at jaycar in the form of PN100 or PN200...
This is handy to know Gav are there many other parts that can be substituded with parts from jaycar?? Could be a good 101 thread if i cant find the exact part numbers i think all is lost 
+1 please as I am an electronic idiot and Jaycar are bloody useless at finding substitutes! (But they are around the corner!)
BTW Rob - nice machine! One on my personal hit list (FP 1&2)
