Florence, Colorado Detections

Believe me, I'd love to, but I only have the one Geiger counter. I can't afford anything else.
What I can say, though, is that it's not just some sudden spike out of nowhere. It goes steadily higher as I approach that area, and drops off as I go away from it. Same general vicinity every time. If I could still go on long walks, I'd go around with it to try to pinpoint it better. Yesterday I took a trip downtown and as always, it climbed up as I got closer to the main drag. It'd been 60CPM at the house and peaked at around 1700CPM in town, and dropped again as I headed back out of town. If it were just doing sudden spikes out of nowhere, or in completely random areas, I'd be more apt to question it, but it's consistent. Always ramping up toward town, always ramping down going away; up outside downtown, down inside any buildings downtown (most of which are brick and/or concrete).
Any ideas for experiments using my current limited equipment resources?

That behavior does sound like a stable and functioning detector. I would consider 2 avenues in your situation: Ask people who work downtown if they know anything about this, maybe show them your detector. If I didn't know anyone, I would start with helpful customer-service types like a librarian or a pharmacist. The other avenue to try is to sniff around some more with the detector, but with some sort of shielding so that it can be aimed. The inside-outside changes you've seen everywhere could very well be sky-source cosmic radiation due to the elevation. Shielding the detector with a small lead 'roof' would show the same change. The in-town rise you see is much higher and must be from a different source. A lead pipe or 5-sided box would show if it's coming from one spot on the surface or from the ground below as you aim to open end.

Are you able to locate some lead sheet? If not, I could send some to you, (unless a USA member can do this - less postage). I would find or tape together a thin wood or cardboard box to fit the detector (tube at the bottom), then tape the lead sheet on the outside of the box (using gloves) and cover it completely so no lead can touch your skin.