I kind of feel like 9Volts may be a bit low for initial voltage. A few years ago I checked my voltage and I was getting 18 volts on a 24volt Superglow. I went through and cleaned all the connections in the system and was rewarded with 22 volts...
Ha! I thought when reading your thread title that you were attempting to avoid the experience I had when I put new lift springs on the truck and then couldn't get it back out of the suddenly way too low garage door.
Your actual problem is one...