Even more PDP-8/A weirdness (was: Re: PDP-8 diagnostics SR settings?)

Update: The first thing I tried was removing and reseating the boot ROMs (465A2/469A2), since they did not use good machine-tooled sockets. Now the boot loader performs normally, no incorrect locations, and OS/8 boots from Drive 0 whether using the boot key or manual start at 0001. Great! So of course, ANOTHER new problem shows up... OS/8 boots and runs, will run PFOCAL, BASIC, give directory listings... But when I hit a Ctrl-C (for example, during a directory listing), Drive 0 Ready goes out, the Fault lamp lights and OS/8 halts. The last instruction showing on the display is 07605, 6213 (CDF CIF 1). I can hit the boot key and as soon as the drive becomes ready again, presumably relocating track 0, the system boots back to the "." prompt.