Hi-8 cassette stuck together

Hi every one. First post on Mac Forums, but long time reader. Great site!

So here's my problem, I have a bunch of Hi -8 video camera cassettes from the 90's and i guess over time through the heat and cold they stuck together. Now even when i try to turn it by hand they still stick. I was going to put them on DVD this past weekend when i took them out of the closet and discovered this problem the hard way, luckly this one was already on VHS.

So my question is if anybody else has any experience or suggesstions on how to get them unstuck? Or any helpful tips.
And please no "i think that this should work" because these are family memories and i don't want to ruin them.

Thanks