Broken heater control lever Hiace 1991

The slider lever that controls the heating in my Hiace 1991 model has fragmented and I would like to gain access behind the dashboard either to be able to fabricate a replacement or acquire a replacement from a wrecker. Is there a simple way to do gain access without drastic actions such as removing the steering column etc which is implied from reading a manual published by Gregorys. This specific problem of the heater valve is not addressed in the 83-89 publication than I have. In fact the problem would appear to be rare considering the lack of information on "repairing heater control" on the internet. Hoping some one among you has had to deal with with this problem.