To quote Lord Blackadder...

[Del]

'The path of my life is strewn with cow pats from the devil's own satanic herd!'

Got a NOS (but not Ford) cap off eBay to replace the one that got nicked, put it on, locked it fine but now can't unlock it!
The key slots in easily, but it's really hard to turn, it won't turn more than twenty degrees or so, and I don't want to be too rough with it in case it snaps.
Is it going to be a case of bludgeoning it with a screwdriver?
Any ideas? It's this type:

[composimmonite]

I assume you tried the key before putting on the car ?
Try pressing down on the cap body with one hand whilst trying to undo with the other just in case the new seal is pushing the cap against the locking aspect and stopping key turning.
I sometimes, although normally with old locks / keys, that you have to "giggle" the key up & down a little to get the internal pegs to line up.
When you eventually manage to hopefully get it undone carefully deburr the teeth of the key as all it needs is a little bit of burr to affect the lifting of the pegs.
Good luck

[Del]

Yep, off the car it worked absolutely perfectly, and it locked first time once I put it on.
Tried pushing down and pulling up, and neither have worked, although I might need to be a bit firmer.
Deburring is a good idea though, ta!

[baggabones]

NOS but not Ford? Think you may have answered your own question

[Del]

Well, it's a cap that's designed for the car, it's just not an 'official' Ford one.

[dodgerover]

Give everything a good soaking with penetrating oil, mines the same on the transit - it only comes off once in a blue moon though

[Del]

I found some 3-in-1 oil under the sink, gave it a good dose of that and left it overnight, and it's just popped straight off on the first go. Tried it on and off a few times and it seems to be working perfectly now.
I wondered if the mechanism was just stiff, having been sat on a shelf for God knows how long.

[colnerov]

To quote Francis Urquhart MP "you might well think that, I couldn't possible comment"