I did a test putting a strip of paper under the "not so safelight" for perhaps 1 minute. Put it in developer and sure enough...black everywhere but the clothespin that was lying on it. So I do need to get a proper safelight.
You can simply buy a sheet of Rosco gel in Medium Red (under $10) and replace the old filter. Most of the older filters will literally melt in water, so you can scrape the glass clean and add a new piece of gel. One 20x24 sheet will fix many safelights.