Newbie here

We are DIY's but sump pumps is something I have NO idea about.

this is what I believe to be our current situation...

we have 2 sump pits. One with the pumps in it, the other is an overflow I believe. (it is sealed) We have 1 hydromatic Pentair Pump and 1 municipal water back-up. The electric pump is only 4 years old. (but I will note that during the first 2 years of our new home, it ran 2 times per hour)

I noticed that both pits were full and had overflowed slightly. I opened cover and wiggled some things and I got the water back-up to go on, however it seemed and sounded very weak to me and only drained about 4 inches of water in 30 minutes. Then went off, then went on and stayed on for 45 minutes without really doing much to the water level. Then I was tinkering around near my furnace, jiggling some run-off pipes etc., then the one of the sump pump suddenly really went off and drained the whole pit.

I couldn't tell if it was the electric pump or the water pump doing the job.

Also I don't think the 2nd pit has drained at all, there is trickles of water coming out of it., I'm not sure how to get it to drain.

I guess some of my questions are

1) how can I test the electric pump to see if it has instead failed?

2) is there some way it could get clogged? if so where should I check?

3) If I replace the pump, I have no idea how to do this.

4) what pump should I get are there some out there with a lifetime warranty? recommended?

5) my challenge will be getting access the pit. The plumbers cut the holes in the round cover then inserted the pipes!, so you can only lift up the lid about 4 inches.