Can't help you with the tape read problem although
the speed issue as you
suggest sounds like a good guess, but as for the
byte count issue: it's 13 hex = 19 dec, which works out exactly for the line
you show when you include the address bytes (everything after the 13).
Lesson: you're up too late at night :) ...but then so am I (!) :/
Thats a big relief... With these hex characters encoded onto tape as two 7
bit ASCII chracters its easy to loose track.
Not once did I think of converting 13 to hex...
Grant