Frequency of faulty NEW engine rpm speed sensor G28 ?

[Jim Hollander at Hot Grips Mfg., Inc.]

My Vag-Com identified a faulty engine rpm sensor G28 on my '91 200 TQ 20v so 
I ordered a new one.  Bentley Manual advised to check that ohms between 
terminal 1 and 2 be approximately 1000 ohms, with terminals 1-3 at open 
circuit, and 2-3 open circuit as well.  When I got the G28 sensor I was 
curious and checked the new one with my ohm-meter and the reading on all 
combinations between the 3 terminals was an open circuit.  I wondered if the 
reason there was no ohms reading between terminals 1 and 2  might be because 
the sensor needed to be positioned over the flywheel teeth to get a correct 
reading.  But if there is a coil inside the sensor shouldn't there be 
approx. 25 ohms at all times regardless of proximity to flywheel teeth?

I installed the sensor, and the reading did not change once it was in proper 
position.  I plugged in the Vag-Com and still the code showed a engine rpm 
sensor with no signal (bad sensor).

What is the frequency of a new G28 sensor being bad, any feel for this... 
anyone?

My other question is:  There are two sensors (G28 and G4) on that aluminum 
cast bracket that sits above the flywheel teeth.  Is the only difference 
between them the color of the connector being tan or black, with their size 
and ohms, functionality being identical otherwise?  In other words, if I 
kept track of the connectors, can they be interchangeable?

Removing the old engine rpm speed sensor G28 was no picnic, and a bit of 
abuse befell the other sensor  G4 (black wire end connector at the bracket 
behind the engine on the firewall) next to it, because after installing the 
new (bad) engine rpm speed sensor G28 my Vag-Com now showed both a bad 
engine rpm sensor G28 and a bad ignition timing sensor G4 too.

It was very discouraging going from one a bad G28 to a bad G28 AND a bad G4 
sensor.  But if these G28 NEW sensors often come in bad, then it all makes 
sense.  Should I just order another G28 and insist on checking the ohms 
between terminals 1 and 2 at the parts counter before accepting it? Of 
course I will bring a copy of Bentley page 28.41 where the 1000 ohm test is 
described.

Jim