OK, can anyone help me out with this?

I have taken apart my petrol cap lock. The only trouble is, the wafers with the numbers stamped on, don't match the key number.

Numbers on keys.

222413 (Not actually in that order)

And the numbers on the wafers....

3x "D", 1 x "2", and 1x "3", and one blank (that looks like a "D")

I've nearly got it to work. I can twist the petrol cap from the back to lock it, but can't do it from the other side with the key. Doing my nut in.

I thought the "D"s might be "2"s, but then I've got a wafer with "2" stamped on it. "D" can't be "1", as there are 3(4?) of them, and only one occurence of the number "1".

Is there some sort of secret code?