Geeetech

The underside of the GT2560 has the pinout for each connector - flip your board over to find out.

Assuming that you will be using the Z-Min endstop, the edge-most pin is marked 'V+', the middle pin is marked 'SIG', and the innermost pin is marked 'GND'.

If your proximity sensor uses 5v power ...

This fix worked for me, with my 7mm acrylic top.

Use calipers to verify your acrylic dimensions - if both are 8mm, a wobbly frame is probably due to poorly tightened bolts.

If your frame is wobbly, the problem may be that the acrylic base plates are slightly thinner than specified.

To check, use a caliper to measure the thickness of the top and bottom acrylic base plates.

If they are in spec (8mm or slightly thicker) then do not perform this modification - your frame ...

It seems like your endstops are not reporting correctly.

Verify the function of your endstops with the 'M119' command.

They should all report as 'open' normally, and 'TRIGGERED' if the carriage is touching the endstop.

I noticed that the wiring documentation (near the end of the G2S build manual ...