I have purchased an ETX-125 recently and have difficulty finding the M43.

m43 is the smaller patch of nebulousity immediately
north of m42:
http://www.seds.org/~spider/ngc/ngc.cgi?m42

Can it be seen with ETX-125?

Yes. Even with binoculars.
The combined nebulousity of m42/43 is a naked-eye
object from even moderately light polluted skies.
Middle star of Orion's Sword.
Can't miss it.