TL DR: I fixed a problem in a basement pump and saved a bunch of money. I feel victorious for not giving up and calling in an expert.
Last week I discovered water in the basement and couldn't figure out where it was coming from. I would have attributed it to rain, but the weather was good. Then, while I was doing laundry, there was a weird rushing noise and suddenly water was cascading down from the ceiling, as if someone was taking a shower up there. I looked into the darkness in the tangle of pipes and heating/cooling ducts up there and felt really worried. It looked like something must be broken up there and an expensive pro would have to come out and fix it.
Then I noticed that these water releases seemed to coincide with the air conditioning cycling on. I did some googling and saw that AC leading to basement floods is common and caused by failures of the condensate line or pump... I looked around again and saw that the line was broken off the pump. The water was actually coming from the pump on the floor which was jetting it up to the ceiling--I had seen the water the pump had thrown up coming back and that mislead me.
The fitting where the condensate line attaches to the pump is called a check valve. It was evident that this piece was broken and needed to be replaced. I found that I could order a new one from Amazon for just over $5. When the part came, I realized that it would be easy to take the end out of the line, but there was a broken piece threaded down into the pump. I could not easily reach it and could not coax it to come out. I almost gave up, but then I tried a large flat head screwdriver. I put it into the old fitting at an angle and tried turning it counterclockwise to unscrew it... and it worked! eventually the threaded part came above the housing and I was able to turn it with my fingers.
I put the new part in and connected the line and everything is working as it should, no more flooding!! !
It feels really good to have done this myself and saved the cost of a plumber/AC technician visiting the house.
It might seem a small thing, but for me it's a victory! I like to take on challenges like this and figure it out.