A tube leak that is located at a joint or is covered by floor material or some other material is difficult to repair, but getting proper access and using a conventional two part glue with a patch may still be the best bet. The "liquid latex" sealants do work. They are difficult to properly apply (rolling the entire boat around to get coverage inside the tube). That sort of repair is usually a last resort. If you have subsequent damage that requires repairs an inside patch (necessary for larger holes or tears) will not stick to the coating. It can be very difficult to remove. So, while the stuff does work, application and further repairs are problematic.
Removing and replacing handles and similar loose fittings is usually not that difficult. If they are already starting to come off you can often grab an edge with pliers and slowly pull and peel the item off. Avoid pulling hard enough to separate the top PVC layer off the fabric itself. Items that are coming unglued, but have areas of full bond strength can be loosened with heat, MEK or my favorite trick where I wedge a blunt edged screw driver into the open edge and wiggle back and forth sideways. Heat should be employed with caution and I always screen off the rest of the surrounding PVC. Mek will attack the PVC itself, so use it sparingly and avoid run off onto other parts of the boat. The mechanical screw driver wedge can damage the pvc fabric too. So be careful! Anything that is bonded too well to come apart easily should be left in place and just glue the released section.
For removing the remaining glue (two part glue does not bond to old glue) I use a soft abrasive wheel made for Dremel tools. They remove material slowly so it is easier to work down to the boat material and not all the way to the textile core. Mek and a strong scrub also can work well for light glue deposits.
If you are using a two part glue do not fail to monitor your environmental conditions. The glue is hydroscopic. Moisture will make the bond much weaker. It's always good to work on your boat in the off season, but the conditions need to be right to get a proper bond. If you have a hypalon boat there is a link for those instructions on the following PVC instruction link. For hypalon tolulene is the preferred solvent.