Zorki 4 / film not spooling on spool

[Armoured]

Guess I was pleased with a recent purchase too early ).

Bought a Zorki 4 recently. All seemed to be in order. However, seems like film is not being taken up on the take-up spool properly:

-Film loads properly to begin with, sits well in the sprockets, the take-up spool turns the first couple of times okay - and the rewind knob turns as it should.
-After the first frame or two, though, the spool seems to stop taking up film.
-Playing with it a bit, it seems the take-up spool starts to 'spin', although when there is no film or other (artificial) resistance, the sprocket is definitely turning the spool.

As far as I can guess, but without support on web:
-When the bottom of the camera is on, it seems to put some pressure on spool, but no direct engagement. Is something missing at the bottom to put pressure on the spool to hold it in place? I see only the part of the nut/level that locks the bottom into place.
-Spool looks to be the correct type, but how do I know? I don't see any mechanism to engage it with the sprocket arm. (The Fed I use does this by having a spool and sprocket that just work on friction, the sprocket part fitting the inside of the spool tightly).

Any other ideas?

 

[Stradibarrius]

Sorry if this is too simple but you have to place the end of the film into the spring/slot on the take up spool...Have you done that?

 

[Armoured]

Yes, film under the spring, hooked on the wee hook.

 

[fidget]

The spool is loose on its shaft? They usually fit with a friction engagement.

 

[fanshaw]

The Zorki-4 has a spool that has internal projections which lock on to the slots on the take-up spindle drum. The drum is designed to slip on the spindle. The grip of the drum on the spindle is controlled by the tension of the spring on the bottom of the spindle. It can be adjusted by stretching the spring.
It seem that either the spool is not gripping the drum because it is an incorrect type or the tension of the drum needs adjusting.

 

[Armoured]

@Farnham: thanks, I understand your description. I can't tell whether I have the right take-up spool, since I don't have a picture of the inside of the spool to compare with. But from a quick glance at the inside of the drum, it has a two-sided narrowing which does not seem to match what I see at the bottom of the spindle, so I suspect it is the wrong type of spool.

That said, I see the spring on the spindle (at the bottom before an aluminium base), but neither that base nor any other part of the spindle seems to compress along the spindle. So perhaps the problem is there. What part of the spindle compresses/tensions?

In the meantime, I've taken a hack approach and padded the interior of the spool's drum with paper, which for now seems to have created enough friction for the spool to hold onto the spindle well enough. I'll try this in the meantime, but look forward to suggestions.

Now, where to find a spool...

 

[Armoured]

Ah, I think I see what the spool should have for it to be the right type - it needs two "teeth" opposite from each other at the bottom of the spool (the part that sticks out). So I think this is the issue....

Thanks for the help, I'll be on the lookout for the right spool.