Never seen the lens, never stopped me before. Does it go through the knob and shaft at 90 degrees?
If it does, then a piece of brass rod from a hobby shop can provide it.
As far as a genuine replacement, unless you can find a source of no longer made bits, I'm afraid you may be out of luck.
Something like a camera repair shop may help but it's not going to be the guy down the street but someone who bought out Canon's old stock.
Finally, I have sent it to Canon to fix it. They were fast and charged me around $120 which wasn't bad...I guess. I can recommend them!