6m old printer. Now doesn't recognise filament insertion  

6m old printer. Now doesn't recognise filament insertion

Hi all,

My I3 mk3S was a lockdown toy, so it's approaching a year old in April. It has been working just fine.

The last couple of prints were interrupted by filament out errors when the filament was still in place.

Today, when I insert filament, the extruder motor does not start, so the filament doesn't advance at all.

I have checked the IR sensor, and it is clean, free of dust, and works fine. When I put filament against the steel ball, the reading changes from 0 to 1 on the IR status report.

I have not altered any of the wiring, but can this come loose or change without affecting the IR sensor state report?

I have searched for this on the blog and knowledge base, but there are so many false hits that I can't find anything useful.

I recently installed the upgrade Firmware prusa3d_fw_3_9_0_MK3S   size 6,783 Kb

I would be grateful for any advice as to how to get things working again. Thanks in advance.