The fix on the flag tube is done by inserting toothpick or something similar into it and matching the broken pieces. Ad a drop of super glue. Make sure it's straight until dry. Also preferably a round toothpick.
For the tube, I would use a strong glue such as J B Weld. I have not done this fix myself, but is the way I would go. Remember to chip the ice away from the tip-up before removing from the hole. They are made of pvc tubing and get brittle in the cold. Also the reels can freeze and split if left in the cold after fishing. I always bring mine into the house to dry after fishing. Hopefully this saves you 2 expensive tip-ups. My son uses HT Polars like yours. Amazingly we have seen the flag tube shoot 10' up out of the tube when a fish tripped them.
..He uses large shiners for the most part, so has the magnet set strong. Once you get the hang of em, I'm sure you will like them...Good Luck....olds