If you've got thermal paste on the CPU or on the socket, there is a very easy solution.

I accidentally got some thermal paste on the CPU pins and on the socket when I removed the cooler and it pulled the CPU with it (this only happens with PGA sockets, never with LGA sockets), I spent hours trying to clean it with alcohol and a soft brush, but it didn't work so well.

I got a contact cleaning spray and it cleaned it in seconds.