Help needed with solenoid wiring

[Venus1]

I’ve got the wireless and solenoid from eBay, for my windlass. The instructions are blurred and faded and useless. I have a wiring diagram of sorts from a similar product, pictured.
Interestingly to me, on the solenoid, the blue wire from the middle spade connector was pre-connected to the nearest terminal/stud (also pictured).
As a total amateur, I can follow the wiring (I think), but have some questions.
1. Am I right in thinking that the middle spade connector, to which the negative from the wireless receiver connects, is meant to remain connected to the nearest terminal/stud above, which connects to the motor as a negative? In the diagram I have represented this by the red arrow.
I can understand if this was so, as they are both negatives...(?)
If this is true I will need a double spade adapter so I can connect the wireless receiver negative to that spade.
2. I can’t check yet, but I think my motor has only 3 connections, unlike the diagram which has 4. Am I right in thinking that two of them can be considered the same? ie connector 3 and the motor negative could be the same? In the diagram I have represented this with the blue arrow.
Thanks in advance, and I hope my terminology is passable.

 

[Rocksteadee]

Don’t assume anything, this probably needs more research. The 4th terminal (lower middle may just be a convenient 0v stud.
Are you in a position to measure the resistance (for electrical continuity) between terminals when off, energised one way and then the other?

 

[pvb]

If you look at eBay listings for the solenoid you've bought, you'll find some include wiring diagrams. If your windlass has 3 terminals, here's a suggestion of how to wire it (including the wireless remote)...

 

[Daverw]

You just wire the remote to the spade as you say, we have the same remote. The remote relay has +ve and -ve red and black then it switches the others switch up and switch down these go to left spade and right spade.

You will need to test with a meter and of course check the actual switching without motor attached, looking at your motor this feeds +ve to terminals 2 or 3 depending on solenoid switching, I may have the instructions but working away until weekend

 

[Venus1]

Thanks for replies, most helpful.
rocksteady, yes that 4th terminal seems to be redundant, as confirmed in the diagram from pvb
pvb, thanks your diagram saved the day for me (I had looked online without success)
Daverw, yes the multimeter was used to check. (But I think you mean motor terminals 1 and 2 for +ve motor feed?)