This compaq was tested a few years ago and the RTC battery was replaced.
I tested it a few weeks ago and the the compaq setup program saw the Type 2 HDD there but it wouldn't boot.
I could hear it spin up so it wasn't 'stiction'.
A dos floppy running fdisk didn't know it was there
There was just the flashing curser
so I pull the HDD apart and my suspicions are aroused where the head arm is positioned when the HDD is runninghttp://s1379.photobucket.com/user/glc/media/IMAG0324_zpscveazheb.jpg.html
by moving the arm with a long thin object toward the edge of the disk, all of a sudden it comes up with the message 'Starting MS-DOS'.
Here's where the arm should be...http://s1379.photobucket.com/user/glc/media/IMAG0323_zpsn5yzfowp.jpg.html
On closer inspection I notice a thin object that is underneath the actuator arm mechanism and I pull it outhttp://s1379.photobucket.com/user/glc/media/IMAG0325_zpshq4ujvsg.jpg.html
Now it boots successfully with the HDD still in pieceshttp://s1379.photobucket.com/user/glc/media/IMAG0326_zps7zdyxg8g.jpg.html
the foreign object inside the arm mechanism was a wafer of paint that had flaked off inside the housing
thats all it takes for your HDD to not work
Here is the compaq back together again, pity I can't easily fix the line on the screenhttp://s1379.photobucket.com/user/glc/media/IMAG0328_zpsgfjq9krq.jpg.html
Now I have a couple of SLT/286's that have HDD problems as well, I'll get to these next I hope
have any of you have had any similar weird fixes for hard drives,?