May I be the first to warn against attempting to fix the slow speeds yourself. Unless you are proficient in camera repair (and some of us are), you may regret that attempt. I understand the attraction of fixing it yourself, but I have seen so many butchered cameras I can say its not always that simple. Along with experience and competence, one will need a set of appropriate tools. Some of them rather specialized. A set of eyeglass screwdrivers is usually not enough
. I will admit here that I ended the life of a couple of RF cameras via my DIY enthusiasm and naivete. Another of my cameras barely made it through its surgery, but I am reminded of the experience whenever I see the awful scars left by using inappropriate tools. Don at DAG camera repair was extremely gracious when he fixed my camera, clearly made worse by my attempts at repair. I appreciate the gentle explanation that I mucked things up, but he could make them right again.
If the higher speeds work fine, ask yourself if you really need the slow speeds. Honestly, they aren't that useful for much "Leica work". There's a reason why they sold many Leica's without slow speeds (e.g., II, IIc, IIf, I, Ic, If, Ig).
If you really like your "new" Leica, it isn't too crazy to consider sending it to an expert service. I prefer DAG Camera Repair for excellent work, but there are quite a few other technicians around (worldwide) who are likely just as good. I know it seems stiff to spend another $150 on the camera, but remember it will be fixed completely and function as new (which is amazing to experience), and the camera will function at a high, reliable level for another half century! Seriously.
As mentioned by others; yes the 3.5cm Elmar does not collapse. A neat lens in my opinion! The addition of a couple layers of tape (I use "masking tape") on the bottom of the VIDOM foot solves the loose fit. Personally, I'm not a fan of the view through the VIDOM. I have other external finders I much prefer -- the little CV metal finder is pretty nice.
Welcome to the Leica club.
It sounds like you have a nice little setup with the 35/3.5 Elmar. If its clean, it should make some very nice photographs. Erik here on RFF has demonstrated that ability numerous times. Look for the pre-war Leica lens thread...