Thought I would post this as a method and make it easier to find for those who regularly confront pinhole and wear problems.
Most of the problems with camera and enlarger bellows occur at the corners of the pleats. Due to the movement of the bellows causing expansion and contraction, it is difficult to apply "stick-on" solutions. The following is something I have used successfully many times and works with smaller maintenance type problems. Bellows with holes that Bubba could drive his truck through require stronger measures or more likely replacement of the unit.
1. Clean all extraneous dust and accumulation from the surface of the bellows.
2. Use a denatured alcohol swab to gently touch up each corner pleat for a fine cleaning. Be careful not to dissolve any coatings, and allow the bellows to completely dry before moving on to repair.
3. Get a container of Plasti Dip. This stuff is in a long thin can and is intended for coating tool handles with a no-slip rubberized coating. It will be necessary to transfer the contents of the can to a container that has a screw on lid, for the provided lid will allow the material to dry up when stored.
4. Tools and additional materials required are a small artist's brush and a solvent such as Goof Off, Toluene, or Xylene.
5. Place a small quantity of the Plasti Dip is a bottle top or something about this size. Drip a little solvent into it while stirring to slightly thin out the mixture. This is important for penetration and flexibility.
6. Extend the bellows outward to its furthest point. Brush a small quantity onto every corner tip and pleat edge (at the corners). The entire vertical pleat may be coated, but only do this if there are apparent wear problems. Allow to tack dry, about 15 minutes. You may have to add more solvent to your mix to keep it thin.
7. Repeat this step at least three times to ensure a good solid coat that will remain flexible. Fold the bellows inward about half way, being careful not to do it so much that the edges contact each other, or are really close together. Apply one last thin coat to each tip in this position and let dry for at least one day.
8. Rack the bellows in and out a few times to ensure that the repairs are solid and flexible. If one pops open, return to step 6.
9. Spray a small quantity of Dry Silicone spray on your paint brush, and lightly apply to each place on the folds that have been coated which could come into contact with each other when the bellows is fully compressed. This will prevent sticking.