Here's the finished article.
It's a fairly decent lump of metal.

Other side

Crew close up

Rear view - seems to have fallen over ....

Size comparison with a Scarab Miniatures Haller Pole ...

The base is thicker than the 2p base I use, it's also irritatingly bowed in the middle but not enough to annoy me.
General impressions are - damn how do these go together! I bought this off Sholto personally at a show and he kindly explained how it went together - it's not actually complex if you're logical about it. NO DRILLING IS REQUIRED. This is important as I did drill into the underside of the cart to ensure the suspension has a strong fit. This was a huge mistake as it meant the cart acquired a forward tilt - which the sharp eyed will notice I've removed by making the front wheels go over a bump. My fault entirely. I used gel superglue and it seemed to work fine but I did have to hold some bits in place for up to a minute before letting go of them to ensure they stuck in place at the right angle. No biggie there. It went together quite easily overall. The biggest complaint is I had to bend the HMG trailer to make sure it could sit properly in the tchanka proper. But it's between the gunners legs and virtually unnoticeable so I'm not fussed. It's also the proper 28mm scale. The troops are a bit short legged but in suitable generic uniforms so this will do for any of the multitudes of sides for the chaos in the time.
There is another Tchanka available - I don't have it but will be buying it next time I see Sholto at a show. It's obviously the same general thing but it has a different cart, and the one display model was painted (properly!) blue and was quite lovely to behold. I think they're £25 so quite an investment but they are the most suitable for the period and a lovely model. Your opinion may vary.
Ordering from Schelturm online .... good luck. Try emailing him or better still phone him. His webpage is hopeless which is a real shame as some of the stuff is really nice and no one else does it. Your best bet is probably getting someone in the UK to buy it at a show and post it to you. He's losing a lot of sales due to that dire dire dire website.