One note: Floyd Rose Guitars has never made "licensed" parts. Their products are generally known as Original Floyd Rose or Floyd Rose Original or whatever.
In exchange for cash, Floyd Rose Marketing allows some other company to use some key design elements, & the name for marketing purposes. The licensee might change some elements (material quality, milling precision) from the original design, or take only a few FR elements into their own design.
As a result, many "licensed" versions are disdained. Those made by Schaller are generally well-regarded (though the name might have much to do with that); those by Gotoh seem to be considered the best, possibly even better than Originals.
One exception (supposedly) to the above is the current Floyd Rose Special Series, marketed as imported by Floyd Rose Marketing & made to their exacting specifications. They are NOT stamped "licensed" but bear a "Floyd Rose / Special" imprint.
Replacing small parts is often a hit-or-miss proposition unless you know who actually built what you have. That is to say, you may have to buy a few parts only to find they don't fit. Some owners just replace the whole shebang with a used assembly they buy off Reverb.com -- it's faster & often cheaper. GFS used to sell a complete kit for $20.95.
Any body know where I can get the appropriate arm?
You mean, something like a 6mm Screw In Floyd Rose/Made In Mexico replacement arm
? Yeah, I might have an idea --http://www.guitarfetish.com/6mm-Screw-In-Floyd-RoseMade-in-Mexico-replacement-arm-chrome-_p_61.html
You might actually be able to use ANY "import" arm, like you'd find on any number of Squiers or cheaper -- if it binds, don't force it, but worth a try.
Sure looks like an MG340
to me. Washburn has been known to change that sort of thing mid-run, with or without changing the model number.
If it really needs that thorough a cleaning, then take it apart first.
For a rosewood fretboard, I use lemon oil I got from a violin shop; not so good for maple as it tends to seep in even the tiniest gaps & discolor the wood. However, it's great for loosening crud on hardware, without risking rust; available online from pretty much any gear vendor.
Cleaning the painted areas takes a little warm water with just a touch of mild dish detergent like Dawn. Of course, you thoroughly dust it off first, & then resist unnecessary scrubbing, or you'll increase the "swirly" scratches on the paint. And use the water sparingly or you risk wetting any damage-exposed wood & possibly swelling or degrading the fibers.
Unless the wiring's been torn out, there's no need for a wiring diagram. That "crackling" could be just about anything, so poking randomly around is unlikely to be helpful.
In all likelihood, it's because of cumulative crud on the jack contacts. First thing, you take a regular 1/4" plug, then put it the jack, then take it out, then put it back in, & dio this about 20-30 more times. Ifthat's not good enough, then you clean the jack's contact surfaces with a cotton swab soaked in alcohol. If that doesn't do the trick, & you don't have any Caig DeoxIT handy, you need to get in & polish the contact points with a little piece of super-fine steel wool (or green scrubby pad). (I've heard from reliable sources that Brasso works too, especially when the metal's visibly discolored with crud, but I've never tried it.)