Dixie problem

Hi all. I have a problem with a Dixie mk1 which may sound silly - since syncing it to another oscillator (a Ladik) it won’t come out of sync - I’ve even tried it in a different case. If you apply another sync signal to the oscillator it accepts it until you go lower than the frequency that the Ladik oscillator was outputting upon which it’ll just stick with that Ladik sync frequency. Just to be clear this is totally without the Ladik oscillator being pactched/powered on/in the same case.