It sounds like in your case, you may be accidentally bending the 2 hole a little, if this is the case, that would make the note sound out of tune and drawing harder seem necessary. See the end of my #2 video, to help you get a clean 2 draw note.. then try bending in a relaxed fashion using the jam trax in steps 5 – 7 for reference.
In answer to the other part of your question, It is possible to weaken the reeds and put them out of tune if you are continually bending with A LOT of force. If you’re bending in a relaxed way (as you should) then a new special 20 or Lee Oskar should last you years, no matter how many times you bend a note.
Hope that helps.. let us know!