Hi, I don't think you can fix it really, I have the same problem with my dishwasher, and find that if you just put the tablet into the dispenser without closing the lid,( therefore allowing the tablet to fall into the machine when you close the door) it works just as well, hope it works for you too!
I had the very same problem, I was advised to put the tablet 'on top' of the cutlery. I do this and it works fine, also good for the little fairy pouches you can get cos they're too big for the dispenser. Hope that helps.
I can't tell you how to fix the door. However, we gave up using the tablet container in our dishwaher ages ago. We simply throw the tablet into the plastic basket containing the for cutlery and away it goes. Everything comes out perfectly clean so perhaps you can try that and forget about the tablet container.