Further to my original posting about coil resistances, this query results
from the fact that, though my old car (G-reg Fiat Tipo 1.4 DGT) would work
perfectly for most of the time, every now and again (sometimes 3 times
within 50 miles then perhaps not for 200 miles) it would run rough and
'peck' for a few yards as if trying to stall, and/or die at a roundabout or
set of lights. Sometimes it would key straight away after that, sometimes it
would need to 'rest' for a few minutes before it would start again. Bloody
inconvenient.

I'd replaced HT leads, distributor cap, rotor arm, spark plugs etc. hoping
to cure the fault but, when it continued, I'd assumed it was fuel
starvation - carb needed cleaning or a vapour lock or something - until I
broke down again last weekend. The recovery guy showed it to definitely be
an ignition fault (no spark for a while then it started sparking again and
fired up). He thought the fault might be in the ignition module on the side
of the distributor.

As a garage could end up charging me more than what the car's worth to find
the fault, I thought it would be cheaper to replace the unit - and, while
I'm at it, the coil - which would leave virtually everything on the ignition
side as new. Stupidly, not realising I didn't need to, I took the
distributor out (but I can sort out the timing later). Having made the
mistake I thought I might as well take it home and clean it up. I took off
the rotor arm and plastic protector and, when I looked inside, I found a
greasy bit of black metal spring-clip floating about! I can see it's snapped
off from an 'L-shaped' clip that is riveted to the top inner steel plate.
The loose bit should go down onto a short plastic (I think) stem that meets
the slotted plastic rod that comes in from the vacuum unit.

I can't really see the purpose of the clip - it doesn't look vital but it's
there - and it's obviously been broken for a while. Which means the car has
been starting and running okay with it broken off!

Not knowing much about distributors (apart from their purpose) could anybody
say, from reading this, whether the loose bit of clip could have been
creating an intermittent electrical short and causing the spark to fail?

I'd value your thoughts. Thanks -

Lez