First, unplug the VCR.
You'll have to take the metal cover off (4 Phillips-head screws), the 2 front feet, (Phillips-head screws), and then the front face-plate (3 catches on top, at least one on the bottom and perhaps 1 screw). Then, you can get at the small button (the circuit board should have it labeled) that is for the Eject.
Now, you can plug the VCR back in and hit the Eject button. After that, you can decide if you want to fix the Eject button with a little bit of glue (mine too broke many years ago, and I go in every few years to re-glue it). These VCR's are solid pieces of equipment (I have the U-52, a U-51 and a U-54), and outside of the Pinch Roller assembly which likes to break every 5 years or so (I just bought 2 replacements from http://www.studiosoundelectronics.com/mbk-37.htm), took about 20 minutes to swap them out, they will give many more years of service than the cheap-o replacements that came after it.
J. Francis, September 2007