Fletcher 6100 error, 'check air pressure' put pressure good

[lastboat]

My 6100 just started giving me a problem . It cut the inside of mat then while coming back to home position it started making clicking noise and the computer said error 'head not aligned' check air pressure.
the pressue is good. ANy ideas how to investigate?

 

[lastboat]

SOLVED- loose knife cartridge, slipped out and was holding up head.