How can I remove the dry factory TIM from the heataink easily?

Hello iFixit, I have another machine I was given to keep, and for the most part, I got it cleaned up nicely

Here's what I did so far

• Cleaned the dust
• Cleaned the fan
• Blew the power supply out
• Cleaned the heatsink dust out
• Cleaned the heatsink fan
• Cleaned the CPU thermal paste

But that's where things are becoming an issue

I cleaned the heatsink and it was fine, but I am now having issues

The thermal paste is so dry because of the dust in the cooler was blocking so much airflow, it's as dry as you can get(!!!)

Here's how dusty it was, and why I know this is dry TIM on the heatsink

I got the CPU cleaned up, but the heatsink just won't clean

Here's how nasty it was, and why I am having trouble, because this dust dried out the TIM

Any ideas to get this cleaned, because I am out of ideas; I tried IPA on a napkin pressed to the heatsink with a tape dispenser to give weight, pouring it straight on and letting it soak, and windex and it's still not entirely removed for repasting

This is what I have left on the heatsink for reference

(no, I don't have any more LGA775 coolers that will work as a drop-in replacement at this point; I used the only one on my E8200 530s)