CPU fan
 

Got a PC to repair and the CPU fan has given up the .. er .. spin .. so (its a compact PC) after 20 minutes of painful part removal .. to get the to heat sink .. I've found no thermal compound between CPU and sink .. now its worked for years like this .. but I've never installed a CPU without the paste .. its an AMD one of the older ones with the small square touching the heat sink ..

Suggestions ? do I leave it as I found it .. or do I use paste ?

I'd put it back with some thermal paste.

Use the smallest amount of TIM you can. It's only there to fill in the fine scratches etc, not glue it down! ;) Arctic Silver is the best stuff.