How do you initiate a Imaging (tftp folder) replication on a receiving Primary?

Following a 'Start Now' from ZCC we can initiate the replication thread on a satellite using 'zac cdp replicate Imaging' (or even a simple zac cdp will do it.

However, we have one Primary that remains in state Pending and want to try and force that to sync.

(The reason we need to do this is that we have to change the content replication methodology to 'use closest content servers first' to get the Default content replicating. However, it appears that this setting also changes for the Imaging replication... So, we have a situation where satellites are trying to get the Imaging content from a Primary that doesn't want to sync from the tftp master...)

Any ideas?