Problem Solved…!
After exhausting all options with the BB itself I started checking cables etc… I discovered that drum output was perfect when I connected directly to my amp…. Aha!
Turns out that I had inadvertently changed the settings on my Bose Tonematch T8S for the BB channel and had overdone the Gate Threshold settings which resulted in only allowing some notes through - Problem Solved!
My thanks and apologies for wasting everyone’s time and appreciate all the suggestions….
Keep on pickin’ & grinnin’… Dave