First thing are the belts oem or some clone?
Try taking the belt guides off the variable speed pulley. If I remember right you have to take the shift lever bracket off.
You can go here. And enter the part number. If you don't have it you can go to find models like mine.
http://www.mtdparts.com/equipment/m..._-mtd%20part&gclid=CNeo8-6kwL8CFRJk7Aod-gcAcQ
I've figured it out ... the 21HP variation speed, 46 deck Model No. 247.288851ä Craftsman owners manual said that belt replacement couldn't be done by owners & MTD/SEAR's designers didn't allow enough clearance between the tractor's´ sheet metal frame and & its under-seat tranny/varidrive system to pull either of its belts off . I finally decided to remove rear axle /tranny combo (8 bolts altogether - two each at end of the axle up through through spacer & upper clamp, two short horizontal, self threading bolts through the side of the frameç—´ sheet metal "box" just above the axle clamping bolts which connect the varidrive/tranny assembly to it & two more which clamp the front of the tranny to a sheet metal frame crossbar: To actually replace belts, I 1st disconnected the tranny belt tensioning spring from the driver;s side sheet metal frame by tying wire to its hooked end, wrapping the other end around a wooden stick to protect my hands & pulling to unhook the spring from the frame): 2nd: removed the seat & battery support straps, jacked the tractor up off the wheel/axle/tranny combo & reached in from above to slip the belts onto pulleys. The t 41 belt went in OK but seemed to be a bit tight (maybe has a deeper V than the original which was too chewed up to tell). The next problem was that my new 91 inch long (outside measurement) vbelts4less main drive belt was definitely too short to replace the 90.8 vbelt described in the Sears owners manual because the OEM belt apparently (the original was too chewed up to tell) has a shallower-than-standard "V" which renders its inside length longer than that of "90.8" standard configuration belt. I also noted that this machine's drive/clutch tensioning system is poorly designed because both of its pulleys are flat bottomed - one should be V shaped. I went back to vbelts4less looking for Sears no 954 4067A & found its apparent equivalent under ”cub cadet , no. 754-4067 (no A) for about $19 plus shipping. Finally, I then looked for/found a new "MTD Cub Cadet Toro OEM Replacement Variable Speed Belt 954-0467A 754-0467 from pantanopowerequipment on eBay for $16.95 - free shipping -which I've ordered.
The source you suggested
http://www.mtdparts.com/equipment/mt...FRJk7Aod-gcAcQ sells the same belt for $36.99 and Sears wants $42.
This Craftsman lawn tractor is a very poorly designed machine because the belts of any sort of belt-equipped equipment should be simple/easy to replace. That weakness is tacitly admitted by the owner'smanual (i.e., you are supposed to pay your dealer roughly ~$200 to replace its drive belts) but is unlikely to be noticed until the warrantee is gone. The home owner/customer's roblems are compounded by fact that the USA doesn't require manufacturers to adopt a rational (standardized) belt description system which makes buying a much cheaper generic replacement part difficult.