On any continuous belt dryer, there are several rollers that have to come out to get the belt out. You may have to use a screwdriver, or allen wrench to remove bearings on each end of these rollers. You may have to remove all the rollers. But, that is what you have to do. Rest assured, the dryer was designed in such a way that it is possible to remove the belt. It is possible that some of the rollers are in slots and the belt holds them in. Don't know without seeing detailed photos. I own Prinz brand, and have worked with Pako brand drum dryers all my life, and in every case you can remove the belt.
Generally speaking, you will likely get better "gloss" if you use single-weight paper. I know, hardly any made, except for Slavich. Most of these big dryers were designed to work with single weight (for gloss) in high volume.