Pentax MX Issue - winder.

Howdy all,
I've been rolling a reel of film off* on my MX, and thought I'd reached the end of said 'film'. It stopped allowing me to wind forwards, but would not fire the shutter either. I attempted to rewind the film, but this didn't give enough feedback (see comment below, it'll make sense) from the rewind.
In short, I now cannot wind the lever forwards, nor take a shot. I cannot see anything that is obviously incorrect with the mechanism when the bottom plate is removed, but can't be certain.

Edit: I had actually had the camera serviced in November 2020, with infrequent use thereafter.

Has anyone else seen anything like this before?

Diolch! - B



*In actuality, there was no film loaded...

I've tried the shutter and self timer and that hasn't worked. The shutter depresses, so is not locked. I've tried the lock-switch too just in case, but that's had no effect. I'll have a look for the little square to the left of the button when I get home later.
Thanks for prompting me to provide more information.

I'll give this a little go later. It was fortunate/unfortunate really, I was selling my other MX, was "finishing the roll" to prepare it for the buyer and then it stopped working.
Unfortunately, I sent off my other one, which was a lovely little example.
Fortunately, the buyer had a great camera as a result.

I've got back to Asahiphoto whom carried out the service, and they're willing to repair at a reduced cost... What that reduced cost is I'm not sure...

Square to the left is showing red, fyi.
Jonathan's suggestion of 'jiggling' hasn't helped either, unfortunately.

Yeah, that's on a shot by shot basis and isn't any kind of permanent fix anyway. I used it when the problem first appeared so I could at least finish the roll.

That's fair. What it seems to be, to my untrained eye, is the winder being 'cocked' and the shutter mechanism not actually triggering anything. I've had a look around and can't see what should be moving versus the 'orientation' the winder/mirror mechanisms are, so it'll probably be sent off...

Right, so I've had a look around. There's a little 'shutter latch' which is tensioned by quite a strong spring under the body of the camera (underneath the slow shutter mechanism).
When the camera is latching, it's almost as if it's 'overwinding', so is returning to it's position of rest. Ergo, it's not latching the shutter, while the winder has completed a full actuation.
It'll be sent off, but it's quite interesting. If I manually manipulate the little shaft of the 'shutter latch' mechanism, I can fire the camera. However, when winding on again, the same issue presents.