About a week a go I purchased an 87 M6 that has a malfunctioning tachometer. Knowing that this is a fairly common problem I purchased two new NiCad batteries and 2 battery holders from radio shack and was planning on putting them in when I got the time. This morning however, after about 30 seconds of driving the tachometer started working and failed to work on my way home. This leads me to believe that the batteries are fine and that rather there is a loose connection somewhere. My soldering skill is not too shabby but id rather not make alterations to my baby unless it needs absolutely it. So what is your take on this? Could the batteries still be culprate or should I be looking elsewhere? I searched the archives but couldn't find much. Thanks in advance.