How well should clutch fluid reservoir lid seal seal?

It definitely doesn't have near an airtight seal as the brake fluid reservoir. It's very floppy and comes off with very little prying.

Is this normal?

 

Good enough to not let fluid out.

 

Will a Good hard impact jar the cover off the clutch Master cylinder??

As long as the fluid does not push the lid off.

When was the clutch Master Cylinder changed last?

It should be as tight as the Brake Master Cylinder.

 

On my first gen it wasn't loose but I wouldn't say that it fit particularly snugly either more so that the cap itself was softer than the brake fluid reservoir cap it could very easily be pried off with two fingers where the brake fluid required twice the effort though also wasn't difficult either.

I never had any issues with it leaking fluid or popping off while wheeling though.

 

Unknown. Truck had 3 previous owners. I didn't know these were wear items.

 

I needs to keep the air/moisture out so it should be tight enough to seal.