I learned this "secret" from Steve and Ray at Pro Musica in Urbana Illinois in the mid 70's. They used a small hi-intensity lite and placed it about 8" from the cartridge while at rest. (Some old-timers may remember the "Pro Musica Phono Unit" which these guys produced, a remarkably musical device based on the Shure V15/3G cartridge.) It is equally important not to overdo it and "cook" the cartridge, however. I keep a small thermometer on the armboard near the stylus. Interestingly, 72 degrees or a little more works well with the Shure also. A related "tweak" is running a small vaporizer in the vicinity of the turntable, especially on cold, low-humidity winter days. Happy listening....
What temperature is your cartridge?????
When I worked at Adcom on the Crosscoil high output moving coil we discovered that we had to measure frequency response and tracking at a particular temperature. If it was warmer the cartridge ( ALL CARTRIDGES) tracked better and were brighter and on a cold New Jersey morning they sounded dull and wouldn't track for beans. Install a lamp next to your turntable and small themometer. Never go below 72 degree F. You can literall fine tune a cartridge by heating it up or cooling it down. It has to do with the compliance of the rubber used in mounting the armature.