I’m frequently called about dryers that take 2-3 hours to complete a cycle. Most of the time the cause is the exhaust vent rather than the dryer. Many houses and apartments have inadequate dryer vent systems which are either too long, or have too many bends. The result is a vent full of combustible lint and a slow-performing dryer. If the top of the dryer is really hot to the touch, or if you smell something burning, investigate further. Turn on the dryer and find where the vent exits the dwelling. Feel for air movement at the outside wall cap. ( Hard to do when it’s on the second story, you need a pro for these situations) If you feel no air-flow, begin to suspect the vent. There are many reputable vent cleaning companies in our area, and this is a home owners task not to be ignored.