Bought a single bud off ebay

My right bud just started sounding much quieter than it should be, my left was still perfect. I tried the beeping of find my buds, cleaning, turning up volumes to max for periods of time to try and fix. Nothing worked. So I bought a single bud off ebay from what appears to be a reputable shop. Bud shows up as promised with directions on how to pair the new bud to the existing bud. Directions are the easiest thing in the world. Press down on the old and new buds together in the case the green case light will start to blink and then return to it's normal light. I tried this 1000 times and the green light begins to blink about 16 times as it should but then a red light starts to blink indicating that they are not pairing. Tried cleaning, pressing at different pressures and angles and nothing. Anyone else run I to this. Apologize for the long post ....at my wits end.