Replacing head on a Rk05j

I have replaced RK05 heads, but I had the proper DEC spare part (:-)) complete with the leaf spring/mounting strip. I think that's right. I assuem the screws go into threaded bushes in the ceramic disk, so you ened ot be very careful when tightening them. I also wonder if there's enouygh free play in thge mounting holes to mean the head azimuth (angle between the gap and the track, basically) will not necessarily be corrrect. Setting that could be 'interesting'. There are 2 allen setscrews per head. One clamps the head assembly, the other is used to push the head towards the spindle,. When fitting a new head, you start wit hthe second oen beacked off, then slide in the head. Put in the alignment disk, seek to the right cylinder and carefully screw i nthe adjusting screw until the lobes on the 'scope screen are the same size. If you go too far you ahve to unload the heads, push the head back by hand, then try again. Actually, it's not that hard. I recoment gettting the RK05 maintenance manual, I guess it's on bitsavers. There is a warning that these screws go into a fairly soft alloy casting, and it's possible to strip the threads. There is an official torque setting, but I guess very few peoplehave a torque wrench that goes down that low On other thing. The leaf springs force the heads onto the disk, and thus towards each other. Wehn fitting or removign a head, make sure they don't suddenly srpign together, or you may damage the face of the enw head. It's a good idea to fit the shippling lock o nthe positioner to hold the carriage back when your are ahdnlign the heads. It's one less thing to move about. I have the EE pack... With that it's quite easy. I susepct you could align for peak output or something like thwt. Maybe putt in the known-good pack, then scre in the adjusting screw whilecounting the turns and noticing when the amplitude starts to rise and when the signal vanishes again. Then start again,m note where the amplitde starts to rise and screw in half as many turns as it took for the amplitude ot flal off. That should get the head over the middle of the track. I don't know how weay it would be, but if possible, start witha bulk-erased pack (rememebr, no servo information on these disks) and format one cylinder (knowing which oen it is!). Then set up on that. This will avoid gettign the heads aligned on the wrong cylinder. -tony