Mastercraft portable thickness planer 55-5503-4 roller drive chain sorokets

Greetings from Toronto eh?

Looks like Amazon.ca

https://www.google.com/search?q=drive+chains+for+a+Mastercraft+thickness+planer+Model+%2355-5503-4+in+Canada

Canadian Tire are Mastercraft main distributors so would get them by special order.

Contact Mastercraft to find a source.

I would suggest searching on line for your make and model of tool, you might be able to find an operating manual that should give you information for where to go for replacements.

I did some searching and it looks like if you call 1-800-689-9928 they will be able to help you out. Let them know the date code, and its size. I really doubt they made more that one 12" planer that year. If that date code is like DeWalt or Delta, that should mean the 7th week of 1999.

look on the right side of the page you can download the parts list or the manual
http://www.dewalt.com/tools/machinery-portable-thickness-planers-dw734.aspx

It is fixable if you are technically competent. All parts are still available online. It could be one of two problems:

1 - The rollers are driven by two gear & chain mechanisms on the height adjuster side of the unit. I did have a drive chain break once.

2 - If it isn't that than the gearbox has cracked / gear stripped under the torque load. This is also fixable, each individual gear and the gearbox housing are still available (10-09), but it requires substaintial teardown.

As you disassemble the unit just be careful once you remove the crossover height adjuster shaft - you don't want to turn one lifter by itself and have the planer higher on one side. It really is a simple teardown, just lots of parts. If you like the planer it is worth it; parts are cheap. If you are like me, you enjoy tearing stuff down to see how it's made and you hate throwing out $200 tools because only one little part broke!

I use denatured alcohol to clean the rollers on my Makita, and it doesn't seem to have harmed them over the years, but I do this infrequently. If your rollers are coated with pitch and or chips they won't feed well, no matter how they're adjusted.
(I don't think this planer has the capability to adjust the spring tension on the rollers, but I could be wrong.) You can consult the manual online at http://www.dewaltservicenet.com/Products/DocumentView.aspx?productid=22538&typeId=7605&documentId=21151
If you can attach dust collection to the planer it will probably help.
Also, the direction of the grain makes a difference when trying to plane boards as dense as poplar, (which has a kind of weedy, roey grain sometimes, that would prefer to tear out.)
For example, if you were feeding the board from right to left of the page, the grain on the side of the board should look like this//////// instead of this\\\\\\, which will have a tendency to tear out and jam the planer. If you can make sure the boards feed through in the right direction, this may solve your problems.
I heartily recommend the wax, as well. And possibly compressed air with a nozzle to blow chips aside.
Also consider the length of the boards and the effect of the drop weight on the planer's rollers if there is not an extension roller in place (or a worker) to hold the board as it makes its pass through the machine.
If you feed the board with the cup side down to begin with, taking light passes to smooth the top face, then flipping it over end over end and feeding the other side in the opposite direction, flattening first one face, then the other, you might have better luck.
Aside from all this, a surface planer isn't a jointer, which is designed to straighten & flatten boards, and portable planers in general won't perform as well as industrial models of the same capacity.
If you will continue to be running a lot of stock through your machine, you might want to consider investing in a used 13" Rockwell or Delta or some such cast iron planer, with rollers top and bottom to facilitate movement of course material. They aren't as portable, but might save time in the long run.
On a final note, there's no replacement for sharp knives. Even the best planer won't drive stock well when the knives get dull.
Best of luck!

Researching Your Model. The Rollers are Chain Driven, but this Planer is a V-Belt Drive. Any slippage of Your Belt? Are the Chains Loose?? (there's a Drive Chain on one Side, and a Driven Chain on the Other Ends of the Feed Rollers) Never Hurts to apply a "Light" Coat of Chain Lube to these Parts(Gears & Chains)
DO NOT SAND THE ROLLERS!! Cleaning them with Denatured Alcohol is OK ( I prefer Brake Parts Spray Cleaner Myself)...the Planer Knife Head & the Front & Rear Rollers all work together as a Unit.
What Thickness are You Trying to Remove?? Usually I don't like removing More than 1/32" per pass...
Have you contacted DeWalt Service?

I'd suggest calling 1-800-689-9928 and speaking with one of the customer service representatives