I guess you need to find two things first; amount of water that well can supply and quality of water (if any contamination).

Hi jewel,
Secure your approach to the well by putting a thick sheet of plywood on the ground that abuts the opening; you can use thick wide boards too. Since it was unknown to you consider the opening of the lip may not always hold some ones body weight without caving in.
Once you have a platform to spread your weight over it will let you work with peace of mind. Assembling a stout cross bar on top of 2 thick posts set back off of both sides of the well will allow you to rig up a pulley.
You want a large gauge pulley so can haul on a thick rope to make work smarter. This rig should hold the weight of the person who is prying out the rocks for a look see. Make sure your set up includes a way to wrap the rope bight to take the load off your hands & not loose it's end - the well worker should not be at risk of a free fall.
3 foot wide opening is very good, but do not try to go very deep into the shaft. Cement cased wells allow very little air infiltration & a person will use up the available oxygen surprisingly quickly. Be on the safe side & not only harness in the worker, but have 2 fit men above ground capable of hauling him up immediately. (The above ground crew must have their fellow's security in mind; no boozing on the job & no wandering off.)
The rocks retrieved will hopefully be small enough to lift into a jury rigged sling or bucket for haul out. Make the worker wear a clasped motorcycle/football helmet (no need for face guard) & stand aside when pull up rocks. If they are big rocks & dangerous the worker should get out of the well before a rock load goes up in the sling.
If you can just clear a path through the rock debris then you can assess the water in the well. Try a fragment of a mirror reflecting sunlight downward. If you see any shine back from down in the well that is your water!
Your well sounds like it was good enough to spend on concrete casement. If the well is on your property it is yours & of unknowable value. I would not commit to sharing a well, by taking a neighbors speculation money or free labor, until I knew how productive it is.

Hi jewell,
I would get three contractors(if you can find that many well contractors) to check out the well and give you an estimate for what it would take to get water from the well. They can answer all your questions and also take all the risk. Old wells can present all kinds of problems and risks. Ask about a yield test, but you might not need it if your are not going to use much water too frequently. If your neighbors have wells, they would be a great source of info and maybe know about your well. Your local water company or board and Ag extension service are other sources of info. You probably don't want to own or rent the equipment it would take to revitalize the well if it is greater than 7 feet. The contractor route is the way to go. It also gives an accurate amount to discuss with your neighbor before any money is spent. JMHO.

I am interested how you would share water with your neighbor. Would he have a monthly volume he could take or if he pays half of the start up cost have unlimited use? Would you install a meter to check usage like a water company? Would you share any maintenance or replacement cost? Just curious. Aloha.

Thank you for the information. I will need to call a contrator to check the well out. I can clearly see the water at about 4-5 feet down, maybe 6. We built a house here in 2007. We dug 450 feet for our new well. I do know that we have a high water table, granted we didn't expect to dig 450. The farm well looks like it is in pretty good shape. I don't think it is very old. I think having the neighbor share with us is a nightmare waiting to happen. You are right Lehua, how would one gage usage? It just won't work. I think it would be best to cover until I get a contrator here and let the neighbor know it won't work sharing it. I do need to find out for sure if it is on my lot. I think it is.

Hi jewell,

Good choice. I would revisit the idea of providing your neighbor with water but as a customer not a partner. Install an ag meter and charge him the cost for local ag water since that is your competition. Provide a source to your property line ending in a ball valve. He takes it from there. Install a pump that give you a flow to equal your needs and his. Everything else he has to live with downtime for repairs,etc. including stopping providing him water at anytime or at a months notice. Put all agreements in writing and dated. Notarized is better. Aloha