Numeric keypad

I am using Amaya 11.3.1 on Ubuntu Linux, and I have trouble with the
numeric keypad. (I am on the road with a travel keyboard that has itty
bitty cursor keys but a full-sized numeric keypad.)
When I turn NumLock off, all other applications work fine with the
cursor keys (KP_Left etc), but in Amaya, strange characters are
inserted. For example, hitting the left arrow yields a Ÿ (U+0178).

I didn't find any entry in amaya.keyboard that would make this happen,
and I don't see how I can add an entry that configures this key. Any
suggestions?

Thanks,

Cay