Hi, Bit more experimentation today. Disabled all the frog juicers. No change - so rules them out. As suggested above I actually read the manual and I am now suitably embarrassed as changing the value of CV55 to one, then adjusting CV65 to 128 has cured the problem without the frog juicers enabled - will enable and experiment some more.   From many years ago, in my computer geek days - RTFM.   Thanks for your advice. Much appreciated.