I've had this issue intermittently for a couple of years, & it’s been getting steadily worse over the last few months, so today decided to install a new neutral switch.
Thanks to the OP’s excellent ‘how to’ guide all went well.
One thing I’d advise is to put a piece of rag/kitchen roll on the top of the swingarm, just in case one accidently drops the switch or locknut. It’ll provide a ‘cushion’ & won’t bounce like it will on bare metal & run the risk of going down between the swingarm & engine cases. you’ll at least have a chance of getting it back to try again.