The lighthouse/basestation noise is caused by a loose plastic part on the axis rotary laser
First of all, sorry for no pictures.
One of my lighthouses started to make extra noise. Noise appeared always after 15-30min the devices was turned on. I've heard this is a pretty common problem for vive owners.
Inside the lighthouse, there is a small plastic part on the top of a axis rotary laser, covering a hole from where the laser beam is shot. This plastic part is not glued in and i think the stress caused by movement or heat from motor makes this piece to break in time. Eventually the rotating laser will start making noise because of this loose plastic part and finally it will break away from its place and fly to who know where inside the lighthouse. In my case the loose part jammed the laser and made it stop rotating but didnt break it.
I managed to glue the part back to its place and the noise vanished.
The lighthouse is built in Taiwan 2016/3. I hope this is a fixed issue.