power window regulator spring

Hey, all...
My '94 Oldsmobile four-door failed State Inspection last week because the driver's side window motor had stopped working (and state law says
that your window must function so that if your blinkers stop working you can stick your arm out the window and signal... or show the other driver the Jersey State Bird). So, I read up on the repair and it was completely straightforward, except that you've gotta watch out for this counterbalance spring. But when I took apart the door, I discovered that the motor was a replacement (making it the second to fail) and the clockspring was missing. I figured that the guy who did the previous repair had removed the spring--or failed to secure it, causing it fly off--and not replaced it. I figured this may have contributed to the motor's failure, as it would be working extra hard.
So I went to the wrecking yard and pulled a whole new regulator and motor assembly from a '98 Buick Skylark. Same part, same casting numbers and all, but... no spring. More than that, there was no provision for one. I pulled the door panel off a '93 Skylark and found it did have the spring.
The spring-free '98 regulator works fine and I collected my inspection sticker today.
So... what's the deal here? If the spring was unnecessary, why was it ever included? Would the motor operate faster or more reliably with the counterweight spring? Or did they redesign the motors? Might my spring-free regulator assembly, with its tang and slot designed to accept the spring, have been a transitional model? Any idea why they may have eliminated it? Any info (or anecdotes) appreciated.
Samuel Wear
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