Buying right submersible pump for replacement.

3/4 HP Franklin submersible well pump /about 20 years old now/ is acting strange lately, after I pumped about 8 thousands gallons of well, filling up swimming pool.
Some small pebble got stock in a check valve /valve after pressure switch in house basement/ causing restarting the pump every 15 seconds as the tank was loosing pressure. It was going on for a few days before it got noticed. I replaced the check valve to encounter another problem - the pressure switch is ticking /there's no click on and click off at set 20-40 PSI. you can hear light clicking and the pressure builds up only to about 30-34 PSI and pump stops pumping. When water is drown from a tap it lowers pressure to about 24 PSI and it starts clicking when pump is activated. The pressure rises higher only when water is not taken any more but it cuts off at that mentioned 30-34 PSI. I replaced the pressure switch but the problem persists. I also tested tank bladder, but it is OK. After that I came to conclusion that pump got damaged somehow and it has to be replaced.
Now I got confused as to what type of pump I got down in the well /I want to use same kind not to go with any additional wiring obstacles/. Presence of control box would suggest that it should be 3 wire pump, by today's standards. I am confused as I have seen on some web link info that 3 wire pump has actually 4 wires coming out of pump and 2 wire one has 3 leads out of it. When I looked at control box I can see 3 wires going out to the well / black, yellow and red/ and the cable under well cap has only 3 leads going down to the pump. Maybe the pump I have is just 2 wire pump, but it is old model /mind it is 20 years old/ and those days they had control box?
Please help anybody. Thanks

Older 3 wire pumps had a control box but, no ground wire. Older 2 wire pumps just had 2 wires, and no control box. The new pump you need will have 4 wires. You can add an extra ground wire to the other three you have, or just cut off the green wire from the new motor. I personally don’t think the ground wire on the newer motors helps ground something that is already in the ground and under water. Yours lasted pretty long without a ground wire didn’t it?

Thank you so much. It resolves all my doubts as to wiring. Hope I will not have to bother you again, though it is good to know that there are still people ready to help. Thanks again.
Waldemar