1961 Transmission question

[JosephStil@xxxxxxx]

List:

I am drawing a bead in my gun sight on a 1961 Imperial Crown Southamption 4DHT 
that a couple of folks on the list are helping me scope out.  This car is a 
solid #4 bordering on #3 and the price is right -- well, it's ok...

I have a question for the transmission experts on the list.

Background:
I talked with the owner this morning and in our discussion he proceeded to tell 
me that the motor runs but that the reverse gear doesn't work.

Question:
What could cause this problem?  I have already heard the following suggestions: 
 1)  the push button for reverse is not actuating the cam/control cable to 
shift in to reverse gear, 2) the reverse band could be broken (first & reverse 
are actuated by the same gear?), or 3) a valve body problem.

Any one of you have any suggestions on this?  If it is one of the three 
suggestions above, what am I looking at in terms of a) fixing it myself 
(remember, Dick Benjamin is my idol, but I haven't anywhere near the skillset 
he has), or b) the cost of repairs if done by a transmission mechanic.

I need your help please.  Thanks everyone.  I look forward to hearing the 
responses.