Buick/Olds: Transmission slips in reverse, buick regal, future thanks

Question
Just acquired an 87 Buick Regal Limited but it has been sitting for about a year or so. It runs great and all but its reverse gear never engaged fully and now it doesnt move in reverse at all. all other gears are fine. I'm stationed in Germany so it has been impossible to find anyone to rebuilt american transmissions. I have serviced the trans but didnt help. I need to get it moving to pass inspection. I will eventually change trans but in the near future.

thanks

Answer
You say you have serviced the tranny...I assumed that includes changing the fluid and the filter? Try adding some of the standard additives available in most places...I'm not sure what you have available there, but here WalMart and all similar store sell a big line of such additives. The "sitting for a year" allows gum and varnish to congeal and adhere to the bands and clutches.Those type additives help remove it.