If your idler pulley goes bad, which they do… there is a switch it hits and it will deny the motor to spin. Replace it and likely the whole idler arm assembly, because it’s much easier and costs pretty much the same as buying just the pulley. When the pulley goes, the drive belt pretty much goes as well. So, new drive belt, new pulley arm assembly, and then likely new drum rollers, as they wear down and usually were the cause for the bad belt and pulley. After that, you check the drum roller axels, as they can wear and cause the rollers to fail . Note that you likely have two sets of two rollers (front and back) and they are threaded differently. If you replace that whole load of parts off Amazon, it’ll run you under a hundred Bucks and you’ll basically have a new dryer.