The thin ring that holds the filter glass in place is probably just loose, easy to fix.
You will see a couple of small nicks in the filter ring, get someone to hold the filter with the ring facing up, then get two very fine pointed implements, something like two safety pins and put then in each nick in the ring and turn clockwise.
However be careful not to put to much pressure on the pins in case they slip out and scratch the filter glass.
The ring is usually threaded.
Leon
