Emu XL-7 & MP-7 User's Group

Can anybody help me.I have bought a secondhand xl7 and cant get the
arpeggiator to work. I have followed the instructions on page 26 of
the manual and still no joy. If I set it to P in the maine preset 
screen it seems to work or at least play a pattern, but if I set it 
to M for master arpeggiator
it does nothing. I have tried every option I can think of in the 
master arpeggiator screen, and I'm now worried that the arpeggiator 
may be broken. many thanks for any advice Steve.