Wow! Looks like a feature. I can think of applications
I take it that this is with your recent success in increasing the PLA temperature to make the clear stuff work?
See if there is a melt bulb that has crept under the Teflon tube and extruded with some thickness to the stainless steel tube.
That can minimize the melt bulb and leave a very small orifice.
The clicks you hear are "pressure reliefs" which can continue (one tooth jump) but the effective extrusion pressure is suddenly released.
Which translates to a thin print. However, this is only a consequence from the restricted nozzle.
Easy enough to fix. Just rebuilt the nozzle... meaning clear out the old gunk and check the nozzle build for excess tube clearance.
Have you found the wire cleaning references?
At worst, there could be carbon buildup. Although some argue vehemently, I know this stuff burns if it gets too hot. Therefore, I, me, my opinion says that PLA and ABS nozzles should not be interchanged. This of course complicates significantly when you throw in temperature modifiers and exotic materials. Filled materials, for instance, can accelerate nozzle wear significantly. Just remember the "value" of one silly little part. I haven't worn one out yet (enlarging aperture), but I have burned one tip. And then sectioned it to find carbon blockage at the final cone once I got the zoom power I needed. Carbon is tough to remove! For the filament, it's like trying to walk directly through blackberry bushes.
Just a word of caution
