80% isopropyl alcohol. Use a soft brush wet with some of the alcohol. Brush around the affected areas. Let it dry and that’s all for me.
I wouldn’t recommend dousing electronics in less than 90%. Feels sketchy. But I have nothing to back that up besides “electronics cleaner” being 99% iso.
Or, run some smaller gauge wire with the cat5 so that you can use it later to pull more through easily. (The wire you pull through later should also have some small gauge wire attached, for the next time)