Your motor pulley is grooved so the grooved side of the belt should face the pulley. Flat side should ride against the idler pulley.

Before I go and replace, rollers, belt, etc. am I missing something?
Cannot say.
Check that the belt is around the idler correctly. There is a STICKY with pictures at the top of this forum.

Also how does one determine when the rollers need to be replaced or is that something that should be done every couple of years?
Usually they start thumping or squealing. They do not need to be replaced unless they are causing a noise.

Try turning the drum by hand, it should turn fairly easily.
Perhaps try this on a couple other dryers to get a feel for it.
Could be that one of the felt seals is jamming it or a front glide could use replacing.

Thanks to the information on this site I was able to resolve a problem with my Maytag Gas Dryer that is about 20 years old. It's still in good condition but I recently had to replace the blower fan cage and I noticed the front drum guides were worn so I replaced those also which required I drill out some rivets and replace with new ones they supplied with the drum guide kit.
After doing all that work and reassembling I was having similar symptoms as posted on this thread. The drum would turn but it sounded like it was rubbing on something like the felt seals were somehow restricting it. It would turn with light loads but sounded like it was rubbing. With heavier loads the drum would not rotate. I took it apart and put back together several times and could not resolve it.
Finally after seeing the suggestion to make sure the drum belt was around the larger part of the drum and not in the channel of the drum, this fixed my problem. Now it works great again. I made the same mistake because they belt just kind of automatically goes down in that channel when you are working on it. To get it out of the channel I simply removed the front panel and while dryer was off reached back with one hand on each side of the drum in the upper right and left corners pulled the belt toward the front while rotating the drum clockwise. Once belt was solidly on the drum I tested it and bingo. Problem solved. I had spent much time on this already and was thinking I was going to have to get a new belt or idler pulley but those looked good and I couldn't figure out why it would have developed a new problem. Turns out it was only caused by taking the dryer apart and putting back together.
Thanks again.
Harding Family.:)