New project - not starting - points cam turns then stops

[prothed]

Hi.  New member here...
I've just taken on a TX750 restoration (never worked on one of these before) and the first job is to see whether the engine runs - and if not why not.
The points, coils and plugs seem to work. Each plug sparks when I flick the points open.

With the plugs out the engine spins over normally on the starter (see video )


But with the plugs in, the points cam doesn’t rotate smoothly – it rotates then stops then rotates then stops (see video )



This doesn't look right to me?  I see that the points are on a separate shaft driven via chain from the crank (as far as I know)
Can anyone confirm whether this is a feature of these engines or whether I'm looking at a major problem?

Apologies if this is on page one of the workshop manual but I'm still searching for one of those too!    

Thank you.

[prothed]

Update.
It now runs.
After spinning over for ages the engine caught and runs on both cylinders.
I still don't understand the points cam stopping and starting, but maybe that's just the way it is...

[scrambler]

Hi, the point cam rotates on the shaft to some extent against two springs that are located behind the points plate and they are part of the ignition advancer unit. Perhaps the springs are broken or fallen off and that`s why they seem to be running like that? Pull off the plate to look at the advancer. Hope that helps. I can`t see any video here. 

[prothed]

Will try that. Thanks.

[overseastwinbiker]

I would think with plugs installed and therefore compression your starter clutch is slipping