[Heathkit] cleaning the grunge

[Ronnie Hull]

I just got a HW101 off the bay, and dang if it didn't work! HOWEVER, lots of work to do here. 
It was in a smokers home. I now have the outside case and the front panel and knobs clean, as well as most of the items inside I can get to easily. The problem is, the PC boards are grunged up pretty bad, in between the small components. 

Anyone have any suggestions on how to clean this up without causing harm? I blew as much of it off with compressed air as I could, which didn't remove much. Its like molasses.

thanks in advance

Ronnie - W5SUM