What's the scoop with cannons deteriorating, from what I think I know.. the cannon lasts about 2k balls.. then disapears.. but u can get 1 free from the cannon dwarf guy.. but people have told me that it's impossible to get one from the dwarf because they are never in stock?

tolk to him and u get a new one free

They are almost always in stock. However, after about 200 cannonballs, you will get a notice similar to "Your cannon is about to deteriorate." When that happens, you can pick up your cannon and set it up again, prolonging the deterioration for another 200 cannonballs.