Coastal 251 bow seat backs

[steve19]

One of the backrests on the bow of my 2019 251 Coastal won’t raise up. The boat had been stored for several months.
Any suggestions? The other side still works fine.

 

[steve19]

Follow up question….
Does anyone know if the screws holding the hinges on the flip up seat back all have nuts on them? The four that are accessible when into up position do, I am going to try to take the other four off from the back edge.