stuart turner SIRIUS staem engine

Hi everyone Mick here in France, i am new to this forum and steam engines in general but have a sound mechanical background and was wondering if
anyone here could assist with my technical problem listed below?
I have just managed to aquire a half scale stuart turner sirius model steam engine and wonder if there is anyone here on the forum that has any knowledge of them? My problem is that when i try and pressure the engine using compressed air it turns about a quarter revolution and pressure locks i am assuming the shuttle valve on the steam chest is miss timed and can anyone assist with info on checking the timing please? Along with the engine i also got the boiler and blowlamp , but no connecting pipework does anyone have any pics or drawings that i can work off to get the engine up and running please?
Here's a link to some pictures of it.
I eagerly await any reply Best regards
Mick in France.
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