I have had limited success reviving stiff lenses on rangefinders without removing them, but there are potential issues that arise from this practice.
More "modernish" lenses with yet fluid, but stiff lubrication can often be revived by injecting tiny amounts of new helicoid grease into the exposed gears and working it repeatedly. The action will smooth-out eventually but it may revert to binding again after a short period.
If the lens has been exposed to dust, and you do this, you make a fine grinding powder that will eventually wear out the helicoid.
If you put too much new grease into the helicoid, it will push out the other side and drop into the shutter and/or aperture assembly.
With really stiff lenses, you run the risk of stripping out the tiny set screws that anchor the focusing scale to the helicoid, throwing your focus chart off or making focusing in general impossible without disassembly and repair.
If you have any camera with the "green snot" type of lube used in early German and Japanese rangefinders, this typically will not work, as the grease does not typically respond to this treatment. In my experience, this grease tends to petrify and the only solution is total disassembly and physically scraping/chiseling off the stuff.
It is a gamble, especially with a lens with an integral shutter, but that is up to your judgement.
