Front glass of light meter broken - does it matter?

I have an ancient and very simple analog light meter which can measure incident and reflected light, but has no spot metering capability. For some reason the protective transparent plastic in front of the small light dome broke. The crack goes across the area covered by the light dome, the dome itself is ok, though.

How likely does this affect my exposure measurements? Can I replace the transparent plastic front with some other piece of plexi glass or are these parts likely made out of some special material?

If the crack is not letting any parts fall out, just use it as is.

My trusty old pentax spot meter took a tumble down about 8 concrete steps a few years ago, and that cracked the internal focus screen. I have left it alone. Last week, the spot dot disappeared, and I tracked it down to the focusing screen having shifted. I turned the meter upside down, and gave it a firm whack with my hand, and for now all has come back into alognment for the time being.

I just last week dropped my old Sixtar (Super Pilot) and cracked the little clear lens. It does not seem to have affected the exposure readings.

If the front glass is clear then you can replace it without a problem, as the new glass will not effect meter calibration.

If you have some clear plastic tape you can just use that - take a reading - stick the tape on, and take another reading - if it changes you need to adjust your exposure by that amount - if not then just use it...