Yep!
That was it. GPSapp does in fact only run when DC mode is forced (Didn't found it documented).
Telnet now also starts. After rebuilding my hard disc I didn't run "devs" which prevents telnetd from starting - this was documented, so my fault.
So both apps run again, many thanks for all your help.
The low memory issue was a very interesting one. Before rebuilding my player I had some mysterious effects which are reported sometimes here, like hang-ups of gpsapp in the long-run. Probably these effects are somehow linked ... we will see.
Fossi