I got off my rump, and fear of screwing things up.
So I'll try to write a semi-definitve guide to detaching, disassembling, replacing drop targets, springs, on Gottlieb System 3 games.
I've done this before, many times - but I remember how painful it is to replace drop targets in Gottlieb System 3s (though not as painful as some).
Hopefully this write-up will help someone else out. This method has been the fastest I've found to use.
The fastest way to do this, in short, is to disconnect and remove the DT assembly, and disassemble the plate from the back.
You'll need 1/4" nut driver (I like the hollow Bondhus variety), flat head (number two tip I'm guessing) screwdriver, some paper towels (I like to clean them off dry, not adding any liquids unless it's more of a restore - then I'll use a tumbler or ultrasonic cleaner,) and appropriate replacement parts.
Also a nice set of needlenose pliers to grab the tip of the spring as usually they're next to impossible to do by hand.
I've found that I need to have some spare parts on hand:
# 10 machine screws, # 10x32 x 1/2" (may be # 8x32 x1/2" also - good to have spare fastners on hand - I've used Albany County Fastners in the past, good selection) - these are for the assembly, but not for fastening to the playfield. PF assembly screws are hex head # 10 x 24 wood screws with self-tap x 1/2".
Lock washers for # 10 screws
Standard # 10 washers
Springs for drop targets, often times rusted out, Gottlieb p/n #18995
Compression spring for DT reset coil - #26739 - also be sure to be careful when removing the reset arm as the spring tends to get lost as does the spring washer.
Drop targets and decals for game, usually found @ PBResource.com.
I don't oil or lube down any of the parts, and if I replace one broken drop target, usually there's going to be another broken one sometime soon - so replace them all if you can.
The best overall tip I can give you when fastening the assembly back is to use a little bit of masking tape to hold the screw on. Nobody likes hunting down screws that fall into some little crevice on the PF or on/under the transformer. Not fun.
PXL_20201130_225633508 (resized).jpgPXL_20201130_225637167 (resized).jpgPXL_20201130_225644654.MP (resized).jpgDrop Target - remove spring from individual DTs (resized).jpgDrop Target - disassembly back pulled off (resized).jpgDrop Target - old DTs removed and warning about reset mech (resized).jpgDrop Target - disassembly back showing screws to remove (resized).jpgDrop Target - replace spring on DT (resized).jpgDrop Target - spring orientation for DT resets (resized).jpgPXL_20201201_000352614 (resized).jpgPXL_20201201_000544444 (resized).jpgPXL_20201201_010202165 (resized).jpgPXL_20201201_010308687 (resized).jpg