[HAM] Blank keys/tones

[step5066 at bellsouth.net]

While playing my Model A, I noticed that there were some keys that seemed to be missing tones. I thought this was because a wire or contact had gone bad on the key itself. I compared the tone on the keys of the great with corresponing keys of the swell via the first black preset key. I found out that certain keys would not play on the first and second preset key of both manuals when I pulled out one drawbar. Is this normal? Judging by the strategic muting of certain keys, it seems that this would be normal. Then again, the closely related muting of these tones could be just a coincedence. Anyone have any insight?