Weird one this, and - if it's been posted elsewhere, apologies - i can't find a similar thread.
This is a stock 1050 in immaculate condition.
Ok - important (i think):
This symptom manifests itself regardless of whether the 1050 is
1] connected to Atari XL
2] booted with or without option
3] powered-up unconnected to Atari XL
NB - when connected there is no "boot error"
now the dumb-ass description of the symptoms
power-up
drive spins for 2 seconds...stops for 2 seconds...driv