From what you have written, I am presuming that it is a second hand or at least a very old unit?
I have read many threads about using one, as I too now have an old one to try and use. From memory of about 30+ years ago though, when I originally bought one, I NEVER was able to get a perfect glaze on any FB (NOT RC paper!!) paper print. Placing the print side upwards gave a nice surface though.
Also, one really important thing, what colour is the cloth covering? My one is a dark beige, so not good for anything. I have read about people who have put them in the wash and then used them but for the low price, I have bought a sheet of virgin canvas to cut up and stitch to make a new one soon.
I will also try the suggestion of 'Tetenal Mirasol' as a glazing agent, as I already have a bottle.
Terry S