It’s good that you’ve already ruled out obvious blockages by checking the pump impeller. Sometimes, a thorough inspection can reveal something small that’s causing the malfunction, and it’s true that a skilled technician might be able to fix it without requiring new parts, especially if it’s something like a clogged drainage path.
As for your old top loader washer, I imagine it’s a bit of a hassle to rely on it, especially when it doesn’t do as good of a job wringing out the clothes as your Siemens. I can imagine it’s inconvenient, but at least it’s still functioning. Maybe after the repair, you’ll have your Siemens back to its optimal performance!