The first step would be to make sure the monitor works. Here is the pinout of the 8 Pin VTR connector.
http://freespace.virgin.net/matt.wai...av/8pinvtr.htm
Make a cable that will go from the RCA video and Audio outputs of a VCR or DVD player to the video and audio inputs of the monitor. Play the tape or DVD and see if you have video and/or audio.
What is the make and model of the 1/2" machine you are referring to?
If you were observing vertical problems on the new monitor it is very possible that the monitor is fine and that the VTR is having problems locking to vertical. This can be caused by the loss of all of the lubricant in the tape which causes it to stick to the drum. If this is the case, the tapes may not be recoverable or it will take a lot of effort to make it work.
I may have service manuals for one or both of the monitors. I'll check.