I have never had any luck fixing a relay but, maybe someone else here can help. Twice now I have spent a few hours tring to fix and then ended up buying a new fogger. I will now buy the same fogger and keep the old one for parts.
Are you sure it is a relay? What exactly is the symtom? The main relay that I know of is the temp control relay. It looks like a small block. It has 3 spade connections. If this is the relay you have or are looking for, this is a relay that can be found in auto parts store. It is used to control electic fans in after market kits for cars. Older cars had hydrostatic fans. To reduce the load of the fan plus the noise of the fan, some of us old timers replaced the belt driven fan with a relay contolled fan.
Did you test the relay with an ohm meter or test light? If you connect from the common which is the spade by itself to one of the two spades next to each other. One should give continuity and the other should not. If you take the temp sendor and put it in boiling water, you should at some point get continuity from the other spade and lose continuity from the first one when cold.
Hope this helps.
I just read some other posts. Naturally there could be relays on the control board. Likely solid state type as opposed to the mechanical relay I describe above.