Vacuum Troubleshooting

Need some advice/outside ideas for trouble I'm having with my vacuum -

 A few months ago (October?) we bought a new vacuum cleaner, and it worked amazingly well. It was obvious very quickly that our old vacuum hadn't been picking up very well in quite awhile. So of course I move all our furniture around so I can vacuum every inch of our apartment in the first week!

After all that, of course the filters needed rinsing, etc. It continued to work well until about a month ago when it didn't seem to pick up as well as it had before - so again I took it apart to clean filters, check belts, etc. There is suction, but everything being picked up is collecting on the filter and not in the canister.

By coincidence we took our vacuum to the local hardware store because of a recall on our retractable cord. While it was there, I mentioned the problem we were having and they did find (and cleaned out) a clog in the system that I couldn't have managed at home. When we brought the vacuum home - same thing. Again, clean filters, and still have the same problem.

My guess now is to buy a new rinseable filter. The company says it shouldn't be needed this soon, but is it possible I've worked the machine so much making up for our previous vacuum that it has worn out? The filters aren't expensive so it's not an issue of money, but I'd hate to keep putting all this effort and worry if it's in vain. Does replacing the filter sound like the best idea? Is there anything else I should be trying?