Digital BW, The Print

I am using CFS rigs from MIS on my 1160 (MIS Quadtone) and 
1200 (Generations Enhanced). On both printers, I have recently 
lost all black nozzles. I suspect that tension from the tubes is 
pulling the black cartridges up, introducing air bubbles and 
causing the black heads to lose prime.

Has anyone else had this problem? Can anyone suggest a 
solution? Is there a way to keep the carts in place? Is it possible 
to wrap a sturdy rubber band around the whole cart/head 
assembly to hold the carts in place? I can't tell if there's enough 
clearance under the assembly. I'm not sure whether tape would 
hold firmly enough. I know the MIS website carries instructions 
for modifying the 1160 cartridge clamps for use with the CFS, but 
it seems to involve a fair bit of work.

Any suggestions would be much appreciated.

Jacques Cornell