ArrowChat

I have recently changed to https on a vbulletin forum.

I have the following message for all Arrowchat avatars....
Loading mixed (insecure) display content "http://www.gravatar.com/avatar/d23115f290e5ab4129ed13f886621cf2?d=identicon" on a secure page

How do I get this changed to https://

What file needs changing to reflect the change to https://

Four days and no reply from Arrowchat?
Looks like I will be moving elsewhere for my chat solution..............