Monitor screen width adjustment?

Hello again, I've got a Sinclair (well, Amstrad really, but it has Sinclair printed on the front) monitor here, which claims to be a QL monitor. To the extent that it has a captive QL-specific signal lead... However, the display is too wide, and marginally extends past the bezel in both directions; only by about 1/4 of one character or so, but just enough to be seriously annoying. So, today, I whizzed the back off to adjust it - but there's no "horizontal size" pot :( There are trimpots for V.size, H.hold and Sub-bright. There's adjusters for focus & brightness (or maybe contrast, it was hard to tell since it was simply labelled "Screen". There's also externally accessible controls for V.hold, brightness & contrast. On the back of the tube, there's trimpots to adjust red & blue intensity (with two pots per colour). It looks like there ought to be a green pot as well, but there's no trimmer there, just a fixed resistor. So, is it the case that I cannot adjust the h.size? Is it a case of go rooting around looking for the component (a resistor, I assume) which sets this, and replace it with a pot? Any advice appreciated. -- Cheers, Ade. Be where it's at, B-Racing! http://b-racing.com