This sounds like a fairly simple repair...although I definitely do not recommend trying to do-it-yerself.
I definitely recommend **NOT** sending it to California Precision Services in Sacramento. This guys insists that you pay a **non-refundable** $45 "diagnostic fee" before he'll say anything about the cost to repair or even the very fact of whether or not he can repair the camera.
I've had mixed results from Albuquerque Photo Technologies, Inc. They seem to consistently over promise and under deliver...and their prices are rather high.
The problem with Nikkormats and all old Nikons, is that Nikon will no longer sell repair parts to independent repair shops. So most independents have decided to not repair any Nikons anymore at all.
Anyway, Zack's might be a good choice. I'm a little put off by their slogan, "We do the impossible"...what about routine maintenance? Surely that's not impossible.
Since this is a pretty simple thing to repair, you might also try some of these...
Professional Camera Repair
4410 Richmond Ave.
Houston, TX 77027
(713)621-3627
contact@professionalcamerarepair.com
http://professionalcamerarepair.com/
Kurt’s Camera Repair, Inc
7403 Princess View Dr. Suite B
San Diego, CA 92120
(888) 673-7811, (619) 286-1810
kurtscamerarepair@sbcglobal.net
http://www.kurtscamerarepair.com/
Camera Service Company, Inc.
4391 West Atlanta Rd SE
Smyrna, GA 30080
Phone: (770) 432-4257
http://www.cameraservicepro.com/
Abilene Camera Repair -- really expensive
401 Neas Rd.
Abilene, Texas 79601
(325) 676-2524
http://abilenecamera.com/
United Camera Repair, Inc.
3830 14th Avenue
Rock Island, IL 61201
(309)786-0950
Service@united-camera.com
http://www.united-camera.com
Dave Easterwood
Dave's Camera Repair
77 Cambridge Court
Chelsea, Michigan
(734) 433-2640
dave@davescamera.net
h
ttps://www.davescamera.net/
Pro Camera Service -- Used to be v. good but seems like its just one guy and his son now....not very responsive.
710 E. Thousand Oaks Blvd.
Thousand Oaks, CA 91360
(805) 497-7240
www.procamera.net