Followup: I replaced the dead PRAM battery and right after the clock still behaved just as it did before. I booted 7.1, set the date and time and now even after sitting for several weeks without a (main) battery the machine behaves as it should and displays the current date and time.
The ProDrive LPS drives usually suffer from sticky rubber bumpers that prevent the heads from moving. I believe there are some threads with pictures on how to fix this.
I agree 100%. Do not use it in this condition as there will be electrolyte everywhere and it might short out one of the driver chips and ruin your LCD. Ask me how I learned that. I was too late with recapping my 165 LCD and half the screen kept glitching. I ended up getting another LCD and...