Finding a leak is often the most challenging part of the repair. Some leaks originate several feet away from where you see a water spot. With roof leaks, water dose not always travel straight down. To get started you need to closely inspect you entire roof.
You should make sure you have a roof leak and not a condensation problem, which is very common in mobile homes.
If you cant find the leak, you may need to coat your entire roof, which should be done every two tears anyway.
PROCEED WITH CAUTION WHEN WALKING ON YOU MOBILE HOME ROOF
Most manufactured home makers say its okay to walk on your roof, but you need to take precautions before climbing on. First check to see if your roof and its trusses appear to be in good condition and able to support your weight. Watch for wet , or moss covered areas so you don't slip.
If Possible make your repairs from a ladder. If you have to go up on the roof watch where you step. If you step on the wrong spot you could split a seam and cause a bigger problem. Try to keep your weight on the rafters which are usually 16-24 inches apart. Another good place to step is along the edge of the roof.