Deunan wrote on 2023-05-06, 21:35:
Heads will move anyway as part of the self-test, and on 3.5" drives these are parked on the platters (closest to the spindle/shaft) but the warming up idea is good. BTW the noise can also be a broken off head scrapping the platter, I don't think I have to explain this is always a KO for the disk. Oh and in case you are thinking about opening the cover to get better access to insides - this will not not help you oil the main bearing, not unless you remove the heads, and all the platters - and with a stepper motor rather than coil you will misalign the heads. Just not worth the trouble if you can't do anything from the outside.
Thank you Deunan for you precious advice
I will never ever open an old hard drive because I know only BAD things can come out of it ... I am not a clockmaker, high tech engineer or someone with gold hands.
Anyway an update on my ST351A/X
I did put a drop of oil on the stepper motor axel opening and another on the center notch of the main motor (had to remove the PCB for that
I did put it in the oven when the temperature never exeeded 60-65 ºC (the oven was already switched off when I inserted it)
Results: I didn't help much and it might have actually made it worse a bit
The hard disk now at boot in the initializing sequence seems to make an extra little noise ... some "dan dan dan" and now struggles to start track zero
I had to run NDD, Fdisk it, and then NDD again ... always will a lot of retry errors
Then I run Spinrite 5 on it and it reported the same bad sectors as before... at least it seems not be developing any more and it stopped at around 240k (0.5%)
So now the hard disk is formatted it boots with MS DOS 5 and the first bytes (boot sector) seems to have been moved to avoid the first inaccessible area....
All that been said the main motor makes a much healthier noise now and the stepper motor runs smooth as I recall it from the old days so maybe the oil and oven treatment did make a little positive difference
Or it may just be because the disk was turned on for many hours for the spinrite that did manage to heal those bearings a bit
Who knows..
Thank for all who replyed !