Mister-e, thanks for the prompt reply!

The original commercial controller for this stepper uses an Amtel micro, driving an array of 8 transistors. It runs well off a 6v battery, and is pre-programmed for a set speed.

I needed a controller with a slightly different speed, and when I saw the circuit I referred to earlier, I thought that would be ideal. It is meant to be a circuit intended to drive a telescope stepper motor of the kind I have.

I am just using the same motor and the same battery supply the commercial controller used, but substituting this PIC16F627 / L293D circuit to drive the motor. So I know there is adequate power available. The L293D is meant to provide up to 600ma continuous according to the datasheet, but I can only measure a max of 40ma when I put an ammeter on one of the coils. If the motor was overloading the L293D I would expect a greater current?

So, am I using the L293D incorrectly? Is the PIC code (provided on the circuit I referred to earlier) incorrect? It just sends a 6 bit signal to the L293D to excite a pair of coils, pauses for a measured time, then sends another signal for the next pair of coils. Surely that ought to work?