I'd get the Kevin VanDam Line and Lure treatment and spray the line with it to help make it cast. The closed face reels, because of design, sometimes will wind up the line loosely inside the reel. After a while this lets the line get bound up, and sometimes even wrapped around the spool shaft inside the reel, meaning the face must be unscrewed and the line unwound from around the shaft to get it untangled again. My dad uses an old Johnson Century 100B reel that recently had this problem. He thought the reel had stopped working and he needed a new one. I took it apart and fixed it in 5 minutes. Just had the line wound around the shaft and wouldn't cast.
In any case, discontinue dunking the reel. Like others said, it is not a good thing, it allows dirt to get inside the reel and collect in places it shouldn't. This will cause problems later that are worse than the one you are having now.
Also, it's not the gears either, they are greased up from the factory and have nothing to do with the cast of those type reels. Only the retrieve.
I believe this is a line issue. It's either the line bound up, or it could be that you've used and cut off most of the line through using it and retying, and now you are down to just a small amount left inside the reel. This would cause casting issues if the line was too low. For that, it's as simple as changing the line out again to refill it. It's simple to unscrew the face of the reel and have a look to see if you have enough line, or that the line is where it belongs and not wrapped up around the shaft, or just wound loosely on the reel only. Start there. After making sure the line is wound right, I'd treat the line with the KVD as I suggested. You can get it online at Bass Pro Shops, or maybe at a tackle store close by. It's about $10 per bottle but well worth it. It increases cast distance for sure, and it does so by making it easier to cast to start with. It seems to soften my line, and that will help a lot for making the line lay right inside the reel on the spool which will help avoid problems on subsequent casts. If you find you need more line, then I'd get the Berkley Trilene XL in the red box in the pound test you want, depending on the size of reel you have. Heavier lines don't work as well on smaller reels. It could be anywhere from 4# line up to 12# as a general range. I'd suggest 6# to 8# for most types of those reels. I like the Berkley Trilene XL for how easy it casts but Stren original is similar also, it is in a purple box for easier identification at the store.
One thing to do that will help with line binding issues is every so often you'll want to make a long cast and then wind the line back while pinching the line between thumb and finger so it winds tightly inside the reel on the spool. Slight to moderate finger pressure is all that's needed. This isn't needed as often when fishing baits that provide natural resistance while reeling them back such as spinnerbaits or crankbaits, but when fishing live bait or soft plastic lures (fake worms for example) then sometimes this lets slack get in the line which can cause the binding problems after multiple casts and slack build up. Every reel needs this from time to time but it's easier to see when it's needed on reels where the line is exposed. On the closed face ones where you can't see the line you may just have to do it as a preventative maintenance about every 20 or 30 casts or just whenever you seem to notice it not performing as well.
Welcome to the site, and welcome to the fantastic world of fishing!!! Once you start, you'll never stop!!! It took me just one time to know I would always do this. I came home from that first trip, consciously aware of that fact.