I discovered a forum/BB several years ago for RV Techs. I reckon it was private or professional. Anyways, I saw the discussion on the circuit cards for RV waterheaters and furnaces.
During the discussion of merits of one brand vs the other it came out that a majority of "their" service calls required the cleaning of the board only. "Cleaning the dust bunnies out from under the componenets".
At the last job I used this information for keeping my furnace and the furnaces of several co-workers and one waterheater going without calling out a service man.
I was just very careful with the tooth brush and canned air while cleaning.
It probably did not hurt that I used to be an avionics tech on F-4 Phantoms either.:)
;)