Well, a couple of thoughts...
(1) Are you sure the output is only 45 watts? Make sure that the radio is setup correctly. For example, if it's in the FSK mode the output is actually controlled by the "Processor Out" control.
(2) If in fact the output is low I'd renegotiate....having said that if you really want a 940 if you get it for a good price you can have it repaired by Clif at AVVid (http://www.avvid.com/
) at a reasonable rate [check his feedback here on eHam].
My 940 has been with me since it was new in 1986 and I lost a driver earlier this year which took out the finals. About $300 to fix and done well by Clif. I will keep this radio until it absolutely dies; it may be an oldie but it's a goodie!
73 -- Dino KL0S