Whether you want to just replace the resistor, or add in a switched resistor, the soldering is the easy part. The difficulty is in the one piece chassis design. The beautifully beefy toroidial transformer has several 20 gauge wires grouped into two sets of twisted pairs. They enter the chassis in two ropes of wire on either side of the transformer location and are spaced narrower than the board. The entry holes are tight and un-grommetted, so if one tries to pull the long snake of wires up to clear access, you risk scraping through the insulation. If you decide to give it a go, you may want to abort if you find removing the board is beyond your comfort level. Why? Because getting it all back in is even harder! So just take this as a stern warning. Don't get in over your head! This from a guy (me) who's been a Mr. fix-it type, with good success, for 3-4 decades.
It would be so much easier if LD had specified a two piece clam-shell chassis. I don’t know how much that would have added to their production costs, but it might behoove them just in terms of their own long term serviceability costs. Perhaps a non-issue in their judgment.
In short, if you want to take it all apart and go for it, you may wish to build a new housing for her, and make life easier in the long term. I can envision a slick hybrid chassis, salvaging the top of the stock unit cut front to back, mounted to an elegant wood bottom with the original face and back screwed to the wood.
Maybe in a year or two…