dashed line displaying too small

Dashed linetype that I use regularly is displaying and plotting at about two thirds the repeat length, in current .dwg, compared to others previous. All settings seem to be the same - global scale factor and current object scale same; use paperspace units for scaling unchecked. Is there some other scale setting?

The .lin file definition is 0.9, -0.9, giving 1.8 repeat length, but when measured it's 1.2 in modelspace. Why is that? In all previous files it's 1.8, no prob.

I just reloaded the linetypes from the .lin file and all went back to normal.

How could the linetype definitions have got corrupted within this one .dwg file?

Is there any way to inspect the linetype, multiline etc. definitions as 'locked in' within a .dwg file? Because once you draw your first linetype, multiline etc within a new .dwg file, its definition gets detached from the external .lin, .mlt etc textfiles where it was loaded from. You can alter the latter and it has no effect within a .dwg file where those linetypes, multilines etc have already been used.

the only way i really get linetypes all mucked up is via someone playing about with the scale, that's the real reason for me with problems involving linetypes.