[cypher]

The Alaska is quite a good size cage so you should be able to fit plenty of things in there to keep him busy.
Make sure he has plenty of substrate to dig & burrow in, if you haven't already completely fill the base with substrate.
Does he have a nice big house other than the little house on the shelf that comes with the cage? If not then you could make him one out of a cardboard box with no base laid on the substrate & a hole cut out for a door. Give him lots of shredded plain white toilet tissue so he can make a nice nest too.
You can make simple toys with just cardboard tubes or boxes, you can hide some of his food or a few treats in those & you can scatter feed rather than just using a bowl, foraging is fun for them & gives them lots to do.
If you can post a photo of your cage set up we might be able to offer some ideas to help.
Have you tried him with Whimzee dog chews? Most hams love to chew on those, the toothbrush one is the most popular.