Hi,
what happened just now is this: i rm'ed /usr/lib/pd/flext/ then rebuilt flext again and installed.
now py says: [x75@u3:~/pd/externals/grill/py] sh build-pd-linux.sh make: *** No rule to make target `/usr/lib/pd/flext/flext_t.a', needed by `source/main.cpp'. Stop.
That looks like if the path to the flext libraries (given in py's config-pd-linux.txt) doesn't fit. Try editing the file and build again.
greetings, Thomas
PS. Someday i'll introduce a new build system....