Bathroom Sink

I am not a fan of plumbing and feel like I make things worse more often than not.  However, I have had decent luck with sinks.

For the past few months, the hot water pressure has been decreasing to the point that it is annoying.  

There is a copper pipe with a screw valve to open and close the water.  I disconnected the connector and had good water pressure.  This was not the problem.

There is a faucet handle at the top of the pipe.  I disconnected this, and expected water to be flying everywhere, but it wasn't.  The problem was somewhere in between.

I removed the connector and scraped out crud on the ends.  I turned on the water and it had good pressure to the end that connects to the faucet.

At the faucet end of the connector, there was a metal screen which I scraped clean and then all of a sudden I had good water pressure.

Something must have been obstructing the flow, but I did not definitively pull out a glob of anything.  I am just happy to have good water pressure again.