This response is for RichK:
Every dryer manufacturer uses a different system to suspend the drum. Maytag uses two rollers in the back with two bottom glides in front. Your Whirlpool dryer has two rollers in back with a plastic ring on the drum and a felt pad on the front panel, one of the best systems in the industry if you ask me. Front/back movement can be a little hard to fix, a more exotic probelm. First, check for rear rollers in good shape. Tread doesn't really wear on these too much, but the hubs can wear down and make the roller wobble. The one on the right seems to be particularly prone to this. If the rollers are good, and the rear seal is not excessively worn or tattered, then drum movement can point to cabinet or rear bulkhead allignment, perhaps due to being tweaked during a move. What this can look like is the drum barely hanging on to the front bulkhead during operation. If it isn't causing a problem with performance, I probably wouldn't worry about it. Some Whirlpool dryers use 2 rollers in back, and 2 in front. These tend not to wear out, but they are noisier.
By the way, the two worse systems in use are by Frigidaire and GE. The former uses a rear ball/cup system that requires lubrication over the life of the machine (former 3-glide front system now replaced by one more like Whirlpool). The latter uses a sort of male/female bearing system with a nylon sheath in the rear that can wear out, with a
4-glide system that holds up drum in the front on top. These glides do wear out, and then the drum will start wearing on the plastic bulkhead that holds them, requiring replacement of that part if it is worn too much.