Start with what you can see. You do not need to know the name of the repair, and guessing at one early is how people end up buying the wrong job.
Each page below takes one symptom and works through the same four questions: what is physically causing it, how you tell that cause from the ones it resembles, how worried you should honestly be, and what the fix costs. Where the answer is “this needs nothing”, the page says so.
The Two That Are Structural
Most basement complaints are water problems. Two are not, and they are the two worth reading first if either describes your wall.
A horizontal crack part way up a wall is a lateral load failure — soil pushing inward, usually clay that has swelled, sometimes frost. On a block wall it typically appears at a mortar course around the middle third of the height. It is not a leak that happens to be horizontal.
A wall that is bowing or leaning inward is the same mechanism further along. Both are load problems, both get worse rather than better, and both are worth an inspection sooner rather than at your convenience.
The Water Ones
Water on the basement floor is the broadest starting point, and the page works through what the entry point tells you — cove joint, single crack, window well, or the sump itself.
Water seeping through a wall covers the slower version, where block darkens in a band rather than running from a point.
A leaking basement wall deals with water tracking down from one identifiable spot, which is usually a much smaller and much cheaper problem than it appears.
The Ones That Are Usually Nothing
Cracks in a basement floor are, more often than not, shrinkage from the slab curing decades ago. There are exceptions and the page covers how to spot them, but most floor cracking in Kalamazoo houses is cosmetic.
A musty smell with no visible water is a humidity problem far more often than a leak, and the fix is usually mechanical rather than structural.
If You Are Not Sure
Photograph it before you clean up. A wide shot, a close-up with a coin for scale, and a picture of the ground outside that wall. Send those through the contact form and you will get an opinion before anyone comes out.