Swimquip Filter?

[Headhunter]

Hi All,
A brief into... Recently purchased a new to me home (June 28th 07) and I am now the proud owner of a 20 x 40 in-ground cement, with liner pool.
I have some limited experience with pools, as when I was young, we had an above ground pool.
Managed to make it through the summer without any real challenges, until this past weekend.
I had just finished vacuming the pool, emptied the pump basket, re-primed the system, than back washed. After back-washing, I turned the power off, turned the handle to filter and re-engaged the pump. I noticed immediately that a small stream of water began to flow out of the filter head, immediately below the filter handle.
I've inquired with a number of "pool experts", who have essentially begged off any kind of repair work, as they suggest that they can't get the parts. I understand that it's an "O" ring that must be replaced.
So, here's my questions to you folks;
1. Should I source an "O" ring myself and replace it myself... I'm reasonalby handy (not a great speller lol)
2. Is this a difficult job? Do you require a great deal of background knowledge to do this?
3. Should I just buy a new filter (quoted price of $500.00 Can. including install)
4. If I do go the route of a new filter, should I be looking at a sand filter or a cartrige filter?
Thanks for taking the time to read and respond! I look forward to reading your responses!
HH

[pool doctor]

sounds like the o-ring on the keystem/ diverter assy inside the multiport valve. Not a hard job. knock the handle pin out and remove the handle, remove the cover screws and take the cover off, the stem that the handle attaches to has a couple of grooves that the o-rings are in. Before you buy them make sure you have the make and model of the valve so you get the right parts.

[Headhunter]

Thanks Pool Doctor... since originally posting this question, I've learned that yes, it is an "O" ring I need to replace.
However, after closer inspection of the filter, I found that one side of the base is broken and I suspect that the filter is one it's "last legs"... yes pun intended!LOL
I find myself now considering a new filter, in the spring, and now I'm wrestling with the decision as to whether I go with a sand filter or a cartridge style filter.
Any recommendations?
HH