Boxpin, rspi, anyone:

How do you PUT BACK the plastic seat that keeps the ball in place at the end of the shifter? I managed to get the old one out--and should have heeded boxpin's advice of leaving it alone more or less--but once the old one was out, I now cannot put the new one in. The seat goes in up to a certain point but won't go beyond that to grab the ball at the bottom, so the shifter doesn't stay put. Volvo must have a tool since force alone won't do it. I used a bamboo "pipe" over it with a rubber mallet so as not to break the seat, but goes in only so far.
Has anyone done this before? thanks