It could be the actual mic failing or the connections may be cracking up. You can remove the module and check to see if the mic is a bit wobbly.
There are some instances of repairs when it’s the poor connections etc. You may not want to try yourself but may find someone you will do a repair if that’s all it is. Replacing the mic is possible but finding a suitable one may be difficult.
The following link is to the last post in the topic, there are other posts in the topic that deal with the mic