Here's a real 'duh' answer: put the right outlet bang through a [delay 10] and have that bang a [1( or whatever frame number you want into the right inlet. That will stop the playback on that frame and the sound. Part of the problem is the sync between the internal states and Pd messaging, which is why the delay is needed.
hi chris - the workaround is doing its job ! thx a lot for helping out
erich