Strewth! 45C! More amber nectar needed;~)
I only use cotton buds if it's really desperate ie out in the field. Most brands have trace amounts of lanolin (oily substance) impregnated, it's in the manufacturers' odd belief that cotton buds are useful to humans and their skin. I favour the use of an architect's type of eraser/rubber, aka the 'plastic' type, on the contacts. Also making sure I resist the temptation to wipe any (insulating) rubber debris off - NOT with my (oily) fingers.
If it needs cleaning fluid I only ever use isopropyl alcohol [spelling?] and lint-free cloth, but I hardly ever resort to fluids.
Stone cold everywhere... the server's airflow arrangement are unnecessarily excessive so as to avoid unexpected hot spots. All fans running nicely. The large tower case is made of a robustly thick gauge of steel. The SCSI HDD is barely warmer than ambient to the touch.
Video card is an ancient Matrox. It runs cool without the need for an on-board fan or any additional flow arrangements around it.
This server has had a cosseted life and this careful environment has enabled it to return a trouble-free operation... until now;~)
I'm going with the dust vector. It's very very fine dust in there - just right for tracking. I'll polish up the RAM's contacts at the same time.