syncrepl not syncing [ CSN older or equal to ctx ]

Hi, I've got a slave that I think I missed out the -w on the slapadd when I rebuilt it recently and it's not picking up changes from the master.

What I'm seeing in the log is

slapd[11886]: [ID 502419 local4.debug] Entry reqStart=20080311204629.000002Z,cn=accesslog CSN 20080311204629.095387Z#000000#000#000000 older or equal to ctx 20080311204629.095387Z#000000#000#000000

Every 60 seconds or so. (My retry interval) type is RefreshAndPersist

Is there an easy way to reset the timestamp on the slave / master so this fires into life or do I need to reload it?

Slave is 2.4.7 and the master is 2.4.8 so it's due another upgrade soon anyway but I'd rather get then synced now and upgrade out of hours.

Thansk, Duncan