In a classic case of the deaf leading the blind, I am trying to help a friend to fix his Space Station. The machine blows fuse F4 the second we switch it on. Referring to this post (https://pinside.com/pinball/forum/topic/space-station-blows-fuse) we have tried to circle in the problem by removing J12 on the aux driver board. The result is that the fuse does not blow, and hence we think the problem is on the playfield.

Furthermore, we have tried to jump the wires to the various pins on J12 one by one, and the fuse blows on pin 6 which would indicate that there is a problem with solenoids 13, 17 18 and/or 20. We reinstalled J12, put in a new fuse, cut the ground wire to the solenoids in question - and this is what we came up with when we bridged the cut wire to the respective solenoid lug one by one:

Solenoid 13 (left re-entry kickback) does not do anything, nor does it trip the fuse
Solenoid 17 (right dock kickback) does not do anything, nor does it trip the fuse
Solenoid 18 (lower left slingshot) trips the fuse instantly.
Solenoid 20 (lower right slingshot) kicks when the wire touches. Not sure if it is supposed to do that?

Both slingshot coils test at around 10 ohms. The re-entry kickback tests at 5+ ohms whereas the right dock is 4 ohms.

We are not sure what to make of these results, so any input would be helpful. Where do we go from here?
SpaceStation (resized).png

Thanks @viriiguy. From the post I referred to I concluded that since I disconnected J12 and the fuse did not blow that there had to be a problem somewhere on the playfield. Are you saying that this is not the case?

Furthermore, will a shorted transistor cause a fuse to blow instantly like this? I would think that the coil just locked on and burned. Or is this a separate problem?

I am trying to understand the schematics. From what I can tell, the F4 circuit goes through the A/C relay, but if this is shorted why does the fuse not blow instantly when J12 is disconnected?
SPACE (resized).png