I guess your split screen cannot be aligned properly as it is not designed to use in your Pentax DSLR, they just cut those old focusing screen from an unknown body to the same size and fit it in - this would affect both metering accuracy and it would not focus correct.
I suggest you first see if your body's AF is correct or just in case the new cheaply built focusing screen is. For the later case, it is unfortunately, then you need to find Pentax to correct the body error. But I bet the most likely case if the former case: it is just that the cheaply cut focusing screen won't work, just trash it if so, I don't think they will give you a working replacement nor refund.
For more about the technical information for all those alignments and how those can be calibrated, you can read my old technical article written (lengthy):-
RiceHigh's Pentax Blog: Focus Calibrations for (Pentax) (D)SLR Bodies and Lenses Originally posted by BBear Using center spot for AF, sometimes I aim at something and I can tell thru my Chinese Split Screen that the AF has not fully closed on the subject.
Whenever this happens, I use the quickshift to manually adjust the focus.
I figure this was normal and thats what the quickshift is there for (ironically available for Pentax!)...
I havent actually tried to compare the AF the camera gives me versus my manual adjustments, to see who is actually correct.
Question is, if the splitscreen shows me the subject is not focused but the AF indicates it is, whats the deal?
Thanks!