The measureable dimensions without removing the spindle on my 10K are: 55.6mm (2.189") OD & 12.54mm (0.494") T. Or, about 2-3/16" OD & 1/2" T.
Due to the position on the spindle, the bearing thickness will likely narrow the field, because any bearing thicker than 1/2" will likely be too tight. I estimate the spindle OD at the thrust bearing location to be about 35mm or 1-3/8".
The SBL thrust ball bearing is separable with a metal bearing cage. If you have your spindle out measure the spindle thickness at the thrust ball bearing location and the thickness at the belt pulley location, and the bearing dimensions to confirm. I don't think Boston Gear or McMaster has a thrust ball bearing listed that complies with the ID and thickness to fit properly.
From the bearing specs I've observed, you'll need the two spindle ODs to spec a proper replacement.
Based on my measurements and assumptions, I think the Schaeffler axial deep groove ball bearings 51107 looks to be a good cross.
Axial deep groove ball bearings - 51107
If you do a Google for "51107 bearing" several results pop-up. Amazon has one listed by VXB on the link below or only $11.69 with free shipping on orders over $35.00. The Amazon page doesn't indicate the origin.
51107 Thrust Bearing 35x52x12 Thrust Bearings: Thrust Ball Bearings: Amazon.com: Industrial & Scientific
51107 Thrust Bearing 35x52x12 ThrustBallBearings
The VXB website lists the bearing for $7.77. If this bearing is USA made, I'll wager the eBay seller discussed above is selling that bearing for $36.00 minimum or $51.00 with BIN. It should be no surprise why he doesn't want to indicate the manufacturer.
One by SKF as well for $27.82 with free shipping on orders over $35.00.
SKF 51107 Single Direction Thrust Bearing, 3 Piece, Grooved Race, 90° Contact Angle, ABEC 1 Precision, Open, Steel Cage, 35mm Bore, 53mm OD, 12mm Width, 8430lbf Static Load Capacity, 3910lbf Dynamic Load Capacity: Thrust Ball Bearings: Amazon.com: I
http://www.skf.com/us/products/bear...single-direction/index.html?prodid=1610011107
I think the SKF bearing is probably the better quality. I'd be surprised if the SKF bearing's origin is Asia. The VXB bearing wouldn't surprise me if it was Asia, but it may not be. You get what you pay for.
If your spindle and bearing measurements confirm my measurements and assumptions, I think the SKF 51107 listed on Amazon would be a good replacement.
Regards
PS - Here's one by NSK, NSK 51107, for $34.82 on Amazon with free shipping on orders over $35.00.
http://www.amazon.com/NSK-Bearing-G..._indust_1?ie=UTF8&refRID=0QCZTH0ZRDKZ86AAGSF5
There's one on eBay for about $31.00 with shipping.
http://www.ebay.com/itm/NSK-51107-Thrust-Bearing-Single-Row-Thrust-Bearing-/151050376828
Here's one by *********, ********* 51107, for $32.45 on Amazon with free shipping on orders over $35.00.
http://www.amazon.com/*********-Gro...23118536&sr=8-9&keywords=51107+Thrust+Bearing
I think the SKF, ********* and NSK bearings are excellent quality. These manufacturers are located in Sweden, Germany and Japan respectively. I don't know about the VXB bearing. You should call to determine their origin.
Amazon lists several more. Do a search on Amazon for "51107 bearing." I think the 51107 series bearings are the proper size, but that needs to be confirmed.
If 12mm (0.4724") thickness is too narrow, you could order one of the 0.032" thickness thrust washers from McMaster to serve as a spacer if the axial play is excessive. The 12mm thickness bearings would be about 0.020" under thickness without the McMaster 0.032" thrust washer and about 0.010" over with it based on my measurement above for the existing thrust ball bearing.
UPDATE: I called VXB and their Thrust Ball Bearing 51107 is manufactured in China.