[RTTY] Off Frequency Question

[KE1JF-Tom]

Why is it that when in S & P  ( mostly the only way I operate ) I always keep the AFC OFF but I'll tune in a station calling CQ perfectly only to have them reply back so far off frequency that I miss most of their reply. Most stations I work regularly each contest ( Bill, like you last night ) reply back dead on the same frequency they called CQ & I tuned them on. I know my TS-2000 isn't drifting & I key it in FSK with a Rigblaster Plus using N1MM & MMTTY like I said, with the AFC OFF. Am I doing something wrong or is it at their end ?

73,
Tom, KE1JF