to restore dry erase boards that are hard to erase: spray a clean board with wd40, wipe dry with paper towels. the wd40 fills in the dried pores of the board that hold in marker ink, making it easier to erase.
this was the hit of father's day. the link for instructions is posted next to this pin on the same board. I used 3/8" x 3' square dowels instead of the bamboo plant sticks. The bamboo did not work very well. My mother (89 years) and one of my grandsons (3 years) loved playing it. Have fun!