Sounds like the float may be bad. I'm not sure what material your float is made from. Some floats are hollow plastic and some are a solid foam block.
If it is hollow plastic, it may have a pin hole causing the float to fill up with gas (which makes it heavier) and causes it to sink. If is sinks the chamber will fill up with additonal gas and cause it to load up.
If it is a foam block. Sometimes these things actually will absorb gas and have the same effect.
It is probably not too expensive to just replace the float so that you have eliminated this as a potential cause.
If turning off the gas temporarily corrects the problem, it very well may be the float.
Don