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Lexus LS Seat Belts
I completely disassembled one of the old ones and now I maybe know the cause.
The front seat belts in the 95 LS have a dual-speed gearbox within the retractor/tensioner assembly.
It has two clock springs that are used to retract the seat belt, a light duty low tension spring and a heavier duty high tension spring.
The retractor uses a solenoid actuated escapment to shift between the two tension springs.
The idea seems to be to use the STRONG spring until the belt is buckled and then lock the strong spring in place and only rely on the light duty spring.
The problem is, apparently, the escapment gets stuck in the low tension position, maybe due to the solenoid armnature becoming permanently magentized.
If you have this problem my suggestion would be to remove the "electric tension reducer" connections to each front seat belt that enables the retractors to "shift" into the low tension mode. Then pull the belt out to the fully extended position 3 or 4 times to be sure the escapment unlocks. With the connection open you will always be using the high tension spring but that's better than paying $300 for a new set of seat belt retractors as I just did.
PIC is of a fully disassembled driver's side front seat belt retractor from a 1995 LS400.