Yes, honestly last time I opened it, it wasn't this dusty! 

After I brushed the dirt off, I used a blower to blow off any residual dust. Could you please recommend me a contact cleaner spray? Is this ok https://www.amazon.com/WD-40-Specialist-Electrical-Contact-STRAW-SPRAYS/dp/B00CMT9TFY/ref=sr_1_fkmr3_1?s=industrial&ie=UTF8&qid=1520721398&sr=1-1-fkmr3&keywords=PCB+contact+cleaner+spray ?

Thanks!