In the absence of a 'scope, I would suggest a logic probe. The kind I'm thinking of shows 'off' on logic 0, 'on' with logic 1, and blinking when pulses are seen. It makes a *major* difference when you know if a pulse exists or not.

Such a logic probe is made with an LED, a few R's, C's, and one CMOS or TTL chip. At retail, the parts cost approximately US $0.50.

In my spare time in the past few days I've been looking for a url with a suitable circuit; maybe someone else has one handy.