It's likely that this could be detected by looking at recorded radar-data as a above-average number of "glitches" at this particular track. But then, I also as

It's likely that this could be detected by looking at recorded radar-data as a above-average number of "glitches" at this particular track. But then, I also assume that modern radar systems have some way to automatically filter displayed tracks for "glitches" or temporary loss of contact to a airplane signal to avoid distracting or tiring out airspace controllers.