Hey Nick,
Just saw this post.
My suggestion would be to look for a local tech who services tape machines for professional audio folks. There are quite a few studios who still use tape and also a small but very knowledgeable community of audio restoration/archive pro's who need well running machines to do their work.
Search the web for studios who feature analog tape for recording or perhaps mastering facilities who do re-mastering work and give them a call.
Another likely place to check are local pro music retailers. Find ones who have been around since the 70's and someone there should know who they use or used to service tape machines.
Most larger cities have tape machine techs who are still active but it does take a little searching and patience to find them.
The RS1500 series machines aren't super complicated so a tech who know how to work on Ampexes, Studers and Otari's should have all the gear and experience to get your machine running right.
You're absolutely correct in not wanting to ship the machine. Even with a custom constructed shipping crate, you're still taking a risk with a heavy and somewhat delicate machine like that.