Take the RTA completely apart, soak and the wash all the parts (except coils) in mild dish detergent. RISE WELL!!!!!!
Allow to air dry on the counter. Reassemble and install new coils.
It sounds to me like old juice inside the screw posts.
Also, if you have a VW/VV/TC device, try a lower setting and work your way up till you find the sweet spot.
Also, I don't recommend applying water to coils. Water + Metal = Rust. Rust, when heated, is toxic.
Be safe and Vape On!