Ok. I have a similar situation. I have my Strida MAS since 2014. I always struggled opening it. I had to put my hand in-between the 2 wheels which is, well, not great. Touching each time the tires. But it seems that is the only I have more power to defeat the strength of the magnet 
But in the last couple of months, sometimes it happens that I struggle quite a lot to separate the the magnet from the metal holder. I don’t know what changed. I don’t believe it’s me )
I found this post and the answers and I tried playing with the screws. The magnet was really tight and not moving at all. The metal part on the other side was very loose, but the bolt holding it was tight as well.
Based on the answers I tried to loosen the magnet a bit and tighten the metal part. The metal part cannot be more tight. It’s designed to be loose no matter how much I tighten the bold. And if I loosen the magnet, it gets worse. It sticks better to the metal part, I believe.
Any other ideas?
Thank you so much!