All of my instrument lights went out so I replaced the rheostat. All the lights worked except for the main gauge lights (large clock, speedo, etc.) which flashed and then went out as soon as I connected the rheostat. I figured my bulbs were burnt, so I bought new ones. I bought Sylvania 168, I think. Anyway, they don't work. Is this because these are not the bulbs from the dealer or have people used these bulbs before? Thanks.