Shaft lifting that was not selected

I have a Schacht with the dobby that they solod in the 90s.Have been using it for 3 years without major issues.

 

Today weaving and shaft 6 keeps wanting to lift even when not selected.  Tried manually picking shafts other than 6 and lift - and it picks itself up.

 

Any ideas on what I should check or do?

Charlene