The analog assemblies are extremely inexpensive (under $5) and fairly easy to replace. You can find them online. I don't think I can post an actual link to a site that sells this type of merchandise, but search the word
Divineo, and you'll find everything you need.
I have had this problem before. It is caused by the springs in the controller being "soft" or having little resistance to the sticks. This is caused by excesive use of the controller's analog sticks. You may fix this by change the whole analog itself, or
buying a new controller. Buying a new controller would be better and easier.