Modify axis constraint after import of Inventor file

Edit: Never mind! I was barking up the wrong tree. All set now.

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Hello all,

I've imported an Inventor file provided by a client. The import looks excellent. There appears to be an axis constraint within the model, such that I cannot rotate the object in the direction I need. I've been fussing with it for some time, but cannot find a way to release this constraint. (This object is horizontally oriented in the real world, but was apparently modelled vertically -- and cannot be rotated to horizontal).

Can anyone point me in the right direction?

Many thanks