The ink window of the 142 was originally a transparent yellow and on many surviving pieces now looks reddish to brownish. This discoloration comes from decades of ink in the pen, which gradually stains the material. It is a normal sign of age and no indication of a part replaced later or of a fake. The small holes in the cap are original too: they serve to let air escape, a design by no means every manufacturer adopted.
An exact year of manufacture cannot be determined on these models, though they can be placed roughly within the decade. One pointer is the feed: a flat feed indicates the early 1950s, a round one the end of the decade. The other is the stamping around the star on the nib. If it is ribbed, that argues for the early 1950s; if it is smooth, for the late ones. Both features are expressly no more than rough pointers and should be weighed together.