Old dry lightbulb grease making contact bad

[slam59]

Went to change rear tail light turn signal bulb and replaced it but after 10 minutes of driving my turn signal was blinking real fast again so took apart to make sure it was in all the way and discovered that the light brown colored bulb grease was old and dried out in the socket and I believe it is not giving a good contact on the new bulb. Cause when I moved the bulb back and forth it would work so I got it in the right position and working for a day only to have it blinking fast again and not working. How do you clean it out and with what and do I disconnect a battery terminal before doing so?