first off welcome to the Pinside RobPCC
basically whenever you score point on the PF the impulse goes to a score relay then to the score reels. so making 100pt triggers the 100 pt score relay ringing the chime/bell unit and adding points. So you need to check out the score relays first in the back box clean and adjust

Yep. Try cleaning the relays.
DO NOT USE OIL OR SOLVENTS!
You can start a fire really easily.
Use sandpaper, emery boards, etc.

Yes always worth pointing that out - RCA1 has it right never use contact cleaner or other solvents in a EM game too big a risk of starting a fire

It would be helpful to have the schematics.

First, start a game. make sure that none of the score reels moves upon game start (beyond them reseting to zero.) Then go to the backbox and find the 100 point relay. Manually move it. does the score reel move? if so, that's good. If not, then there's your problem. (This relay, usually the "N" relay, has a contact that moves the actual 100 point score reel. Perhaps the contact is dirty or mis-adjusted. I rarely clean switches - more often they are mis-adjusted.)

If the score reel does move when manually depressing its associate relay, then you have another problem. On 4 Square, i believe there is a bank underneath the playfield. when you hit one of the square number targets on the playfield, a relay engages and changes the state of that target, because of the switches on the associated relay. There's a good chance that relay has some mis-adjusted switches. again a schematic would be helpful.

Nice work.

Be carefull that the alcohol dries fully, but yeah, not a huge worry. Electrical contact cleaner and lubricating oil are big fire traps. The electrical contacts spark quite a bit, even when working correctly. There's some scarry video of cleaning gone wrong out there.

You might want to look into flipper re-build kits. There are multiple vendors that sell kits for most machines.

The weak flippers may be a maladjusted, dirty or broken end of stroke switch. Look at the underside of your playfield at the flipper area. You'll see the coil and mount, the metal plunger which is connected by a bakelite strip to the crank.

The crank connects to the flipper shaft.

The crank also opens the end of stroke switch.
Initially the flipper has maximum strength, drawing a lot of electrical current to bat the ball. But the flipper doesn't need all that current flowing to hold it extended so that's why the end of stroke switch opens.

If the switch is permanently open the initial high current portion of the coil won't work so you have a weak flipper. The spring works against the working soloniod so that's why tightening it made it worse.

Alternatively, an end of stroke switch that is stuck closed will not release the high current part of the flipper coil as long as the flipper button is pushed in and the high current portion of the flipper coil will remain on. The result is an overheated or burnt flipper coil.

BTW, that looks like a fun game to play. You definetly need that flipper power to get those upper targets. The score grid in the middle of the playfield look interesting!

http://www.ipdb.org/machine.cgi?gid=940

Be careful with extreme high and low temps which a garage can have as it is the destroyer of Pinball Backglass.

Make sure pinball machines are in a temperature controlled environment in general.

4 Square is a great game as I own one as well.

Have fun with it.

Ken