Ooh, excellent guess and a good song...
Lady Love (Robin Trower, 1974, "Bridge of Sighs" album (4-20-1974), authors Robin Trower & James Dewar, length 3:21)
...and the date is perfect, but that's not it. I first heard excerpts from the "Bridge of Sighs" album in spring 1975, and I later bought the album in the late '70s, so I would have recognized the mystery song if it had been on that Robin Trower album. The riff in the mystery song was *much* closer to the notes of the JJF riff, unmistakably so, and the riff was quite repetitious, played at least several times in a row, not just once as in that Robin Trower song.