jsolette / isolette repair questions

Hi-
I just got my first Agfa Jsolette with a Compur-Rapid and am hoping someone could tell how to fix some issues.

1 - after shooting a perfect roll, suddenly the shutter release would not depress enough to fire the shutter. I opened the camera up to find (as you see in the images) a whole mechanism there that seems to slide, click and prevent winding/exposure. when i slide this all the way to the side, the shutter fires fine. There is nothing on the outside of the camera that seems to allow a user to access this slider, other than a little round window next to the shutter release. (see image). There is also a sliding button on the outside of the camera, near the shutter release with a "T" and an arrow. This seems somehow related, though I am not sure how. I can see that the two things interloc with the shutter trigger...but I am not sure how they work, what they are supposed to do, or if they are functioning. Any help?

2 - I googled and foundthis same issue somewhere on a different camera but I am hoping someone will let me know if it is pertinent to my camera: shutter speeds 1, 2, 5, 10 and sometimes 25 stick. I can assist the shutter cock and get the shutter to close, but if left alone it stays open. Also, 500 is incredibly hard to cock. I read on a site that I can open up the front and soak the stuck slow speed escapement in lighter fluid. So, my question is: is this pertinent to my camera? can I do this? can I leave the shutter in the camera, or do I need to remove it to "soak" the stuck slow speed escapement ?

3 - am I crazy or is there a little button missing from the shutter trigger? if so, can I get a replacement?

4 - what is the "T" slider for?
Thanks All!