A homeowner can hang some doors solo, but not the torsion-spring, wall-header work that most Westwood installs involve. Torsion springs store enough energy to break a wrist or worse if you don't know the winding sequence, and on a house from this era with an original header, you're also often shimming or reinforcing framing you can't fully see until the old door is out. Where DIY makes sense: swapping weatherstripping, lubricating rollers and hinges, tightening loose track bolts. Where it doesn't: anything involving the spring, the header, or the opener's electrical box. That's not a sales pitch - it's where the injury numbers on this kind of job actually come from.