Today, I went to switch my Heidenhain TNC151 from Conversational to ISO mode; which, according to the Bridgeport manual, means "press Mod, up arrow until you find user parameters, then ENT".

I can get to the User Parameters menu item, but pressing ENT does nothing. Up/down arrows continue to navigate through the MOD options.

The rest of the machine appears to be working normally.

Any ideas much appreciated.

Cheers,
Ade.