I see your problem, and it's fairly common. The leads are heavy and will concentrate the bending moment on the joint.
It's time to upgrade the lab:
Purchase some Kynar or Tefzel insulated wire wrap wire. This is small and resists solder heat.
Likewise, some Kapton (polyimide) tape will be a great help holding things in place and providing strain relief.
As usual, you should keep a flux pen, some acid brushes, some 95% or better isopropyle alcohol, and some solder wick handy. Solder wick degrades quickly, so keep it bagged with a silica pouch when in storage and flux it a bit to improve its ability.
It's also handy to 5 minute, two part epoxy handy. But not JB weld for electrical work. Usually the clear kind that comes in separate squeeze tubes works best for me. You can tack wires with it or make dams using tape and use it to mold.