1987 G50 - Strange Clutch Noise

[NEUN_ELF]

Hi everyone.

I bought my first 911 several weeks ago. It is a 1987 Targa with 170k miles on the clock. Car is in great shape and has been very well taken care of. Had a PPI done by a reputable Porsche shop in the Los Angeles area and the mechanic found no issues with the car. Compression was very good and leakdown less than 5% on all cylinders. Transmission shifts very well.

I have noticed a strange issue with the clutch. It makes a sort of faint whirring/grinding noise when fully depressed at ~3k RPM's or more (not at idle, however). It can also be felt very faintly in the clutch pedal. I first noticed it shifting between gears. When taking off from a stop in first, there is no noise as it does not occur at idle no matter how far I push the pedal.

The noise also does not occur until the last 20% or so of the clutch pedal travel (well past the bite point), so I can avoid the noise by clutching in around 80% between shifts.

Today, I pulled back the carpet and took a look at the pedal box (for a separate project I was working on) and noticed that a small metal pen had actually gotten lodged in at the bottom of the clutch where it meets the floor in its resting position (i.e. when my foot is off the clutch). It was lodged such that it was limiting travel by a TINY amount, a millimeter or two. But, it meant there was no slack in the clutch, and I fear there may have been very very faint pressure on the fork/release bearing at all times. It was a truly tiny amount of travel that was limited by the lodged object, though.

I'm concerned that this has worn out the throwout bearing over time (no idea how long the pedal had been like this). My car does have the upgraded fork and tube - was done in 2005 by John Walker in Seattle at the same time he rebuilt the top end.

Does anyone have any other ideas as to what could be causing this RPM-dependent whirring/faint grinding sound upon depressing the clutch? I've adjusted my pedal stop and am able to shift without making the noise, but I'd like to understand what is happening here just so I can plot the best path forward.

I made a quick video in which I attempted to capture the noise. I first rev to 3000 RPM without using the clutch (no noise). Second, I rev to 3000 RPM pushing the clutch in around 80% of the way (no noise). Third, I rev to 3000 RPM with the clutch in all the way (noise). Don't confuse what I'm describing with the more distinct rattles in the video - my car is quite noisy as it has the Wevo shifter, PSJ coupler, and RS carpet kit without sound deadening. You can hear the noise from 0:22 to 0:30 when I let off the clutch.

https://youtu.be/SW1TMLDG2qk