How can I verify e1 clocking setup using an ISDN analyser?

I am hiring an ISDN analyser which I am assured "does L1". This I agree would be necessary to independently verify the clocking setup of an E1 trunk between a Cisco IOS voice gateway (AS5350) and an NEC PBX (Model not sure).

The AS5350 is set to drive clocking/provide clocking at it's end. The NEC is set (I am told) to derive it's clock from the line. In fact there are 3 E1 links between these 2 devices, all 3 have same clock setup.

We have symptoms (intermittent faxing issues, slow couting up of errors on AS5350 end) which influence me to want to independantly verify the clock setup at both ends. Industry colleagues tell me that that an ISDN analyser properly equiped should be able to tell from the signal it examines from each  end if that end is clocking or being clocked by the line. I have researched the matter thoroughly but no one seems to know much and there is not much documentation out there.

This suggestion that an analyser would be able to tell me this information seems to be coroboroated(sp?) by the theory which in my understanding is as follows. The line encoding in our case is HDB3. HDB3 like other encoding methods have measures designed to deal with the 1's density problem. In the case of HDB3 a long series of 1s does not present a problem. A "violation" code is appearantly inserted where there are 4 or more 0s to be transmitted.

Presumeably it is this violation code that a L1 capable analyser will see, which would imply that the line is being clocked from that source.

Any comments appreciated, including those dealing with these questions
- How often might this (clocking) information be propagated by a clocking end?
e.g. Do I need to be lucky in having the analyser on the line when there is a clocking signal? Or are these signals likeyl to be sent often?
- Is this a routine matter for an analyser? My industry colleague tells  me he has seen this feature on an HP analyser. I am hiring a NetTest Lite 3000E.
- Might this or any other analyser be able to examine the quality of the clocking? etc