One of my basement showers has very low pressure. Another shower in the same room and the sink are fine. The pressure was fine two years ago and then dropped after the city did some work in the area. It fixed itself after a month. The problem re-appeared again about a month ago.

I've tried bleeding the entire system but have had to success.

Welcome any ideas...

I would check the shower hose or head for a screen and see if it is clear. If not clean or replace the screen(s).

I would check the shower hose or head for a screen and see if it is clear. If not clean or replace the screen(s).

The shower head is off. Hot pressure it great. Cold pressure is almost non-existent.

The shower head is off. Hot pressure it great. Cold pressure is almost non-existent.

From what I have read on this site about the same problems that you are having, it appears that you may have a clogged line on the cold water line and it could be at or near the faucet. Close your main and open both faucets. Remove the cartridge or valve stem and you will likely find debris. Not sure how to remove, try to give a model/brand and maybe one of the experts here can walk you through this.