A "loud motor type sound" can be the brushes riding against a poorly-machined commutator.  It will either cause the softer carbon brushes to wear out faster, or the harder copper commutator sectors to eventually smooth over and quiet down.  You can dress a commutator , if that's the case, but it has to be done very carefully and properly.

Sent from my iPhone

On Apr 9, 2013, at 8:09 AM, Jeff Lincoln <magikvw@GMAIL.COM> wrote:

> I don't know anything about brushes - but it's not a lack of lubrication
> type sound. It's just a loud motor type sound. As far as testing goes -
> sure I made sure it ran on all speeds but you don't really notice the
> sound, or at least I wan't paying close attention to that at the time.
> 
> Thanks,
> 
> Jeff
> '85 GL (Gertie)
> '78 Bus (Melissa) Patty's Bus