A1 Reading Build Plate Too Low

Hi all,
Sorry if this is a rookie question, but I have had a recent consistent problem with my A1 printer in that it consistently reads the plate as being lower than it actually is. It seems like something that grew as a problem over time. There was a single part I was printing many times and the parts gradually grew worse and worse.
I have tried all the usual suspects, recalibrating many times, swapping out the hotend, and cleaning inside the area where the hotend is placed. A while before this I did have a big glob of filament get inside the silicone sock, which I cleaned the best I could. The clamps for the hot end are a bit stiff now, but it doesn’t appear to impact their seating location at all. I’ve looked at the eddy current sensor, but I don’t see any sign of damage, and the wires appear to be intact.
When I home all the axis the tip of the hot end is touching the build plate, you can’t move a piece of paper under it.

As you can see above the first layer always comes out bad and the rest of the model typically has a “squished“ look to it.
Any ideas as to what might be the problem or any workarounds would be greatly appreciated.
Many thanks

The usual suspect I would point towards [and wasnt mentioned] is the Heatblock Assembly Screws. Have you checked those? Unclip the nozzle. Fully remove the 3 screws holding the black heatblock. Gently fold [wires attached] the block down towards you, revealing 4 more screws that hold the nozzle holster. These can get loose over time, and if the nozzle deflects in the holster during calibration, your Z gets messed up.

Many thanks worthy artificer. I have done as you suggested and there was some old filament globs back there along with the screws indeed being loose. I have also found, however, that the hinge which holds the small metal clamp that holds the hotend in place has been frayed so much that the clamp continually falls off. That could contribute to what I am seeing and likely requires me to purchase a spare part for that assembly.