starter solenoid problems

[skr]

ok, so this morning i had some starter problems. as in i turned the key, cranked for 1-2 seconds and then it souded like the solenoid retracted while the starter was turning (as in hearing the starter turning without turning the engine). i checked the solenoid wires, banged in a little with a wrench, gave it another try and the same thing happened. so, half hour and a cup of coffe later i'm removing the starter in -7 degrees celsius. Another half hour later and a lot of freezing like s%^t i had the starter out and the solenoid off. (thank god for lots of space around the m21 and a lot of extensions)
so the solenoid had a lot of dirt or something in the hole that the round cilinder goes in preventing it to move right, and some shitty connections made by the P.O. (damn that ******* was a sloppy mecanic)

now i want to test the solenoid while off the starter to see how it works but not sure what the 4 connections are . i know that the copper one is + for the starter and i guess the other big one (steel) is + allso because i was getting voltage between it and ground. the 2 small ones (lateral are labeled 30h and 50. which one is + and wich one is - ? 30h seams to be connected with the copper one so i guess it's + , meaning that the other is - .
Am i right? i whouldn't want to connect it backwards not to fry the solenoid.
i attached an image of the solonoid .

[skr]

well i kinda figured it out by myself. the 2 big ones are + and they connect when the solenoid gets to the bottom. the 2 small ones are + and - for the solenoid itself, feeding it power when u turn the key. so besides engaging the starter motor it also acts like a switch.
am i right?