HP 7550A Plus Plotter and HP 7550B Plus Plotter - "Lower Cover Press Enter" Error
The most probable cause of the "Lower cover press enter" error.
The pens are incorrectly loaded into the carousel. Remove all the pens from the carousel and reinsert the carousel. The error will go away if this is the problem. Reload the pens correctly.
Bad cover sensor or part on the cover has broken. In both cases the plotter would need to be serviced. Call (800) 243-9816 and speak with an operator to locate an authorized service dealer.
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