Theme consistency - is this a non-starter?

[Stummies]

Hi all - working on a puzzle where the theme involves replacing -CKS with -X in various words to create punny phrases. i.e. CHANGE THE LOX ("Replace a smoked fish platter?" or similar clue).

Question - I have 4 phrases I think are very funny. In 3 of them the X word falls at the end of the phrase as above, but in one themer it is the first word in the phrase. The letter swap is consistent throughout.

Is that a no-go because the theme is structurally inconsistent? Also what if it were two answers with X at end and two with X in first word so it's more symmetrical? Thanks for any help!

[mmcbs]

Yes, three and one might be a knockout. Two and two would be better, and probably acceptable. All in the same position would be ideal.