Got a few of those 1970s decks at home, so I’ve been doing a lot of that same work. The key is to keep the heads clean and the tension springs in good shape – a little dust on a head and you’re looking at hiss in a second. If you replace the caps and recalibrate the bias, you can recover most of the mid‑range punch, but the high‑frequency tail will still bite unless you do a proper track‑leveling. It’s a lot of small, precise steps, and if you skip one, the whole tape turns into a hiss‑fest. The trick is patience, a good pair of tweezers, and a habit of checking each part before moving on.