ScotSunnergren,
First let me add my welcome to the Shopsmith Forum and add to what has already been posted. Your Mark 5 was made in August 1954 and has the "A" Headstock. You already know that the logo plate on the back has no access hole under it. That is true for the "A" Headstock and was changed on the "B" headstock. Some owners have purchased the "B" headstock access hole cover and made their own access hole. That is an option for you. The current "C" Headstock access hole cover is different from the "B" Headstock access hole cover.
Unless a previous owner has modified/upgraded you headstock it has a 3/4 HP motor and uses the Gilmer Drive. Yours should have the Clutched Gilmer Drive Sleeve but due to it's age may need a little work to have the clutch action working correctly. The clutch was one of the early changes made to help prevent the Gilmer Belt from breaking.
As has already been suggested opening up the Headstock would be a good idea. Not only will you be able to preform cleaning and the needed maintenance but also will allow you to better inspect the different parts that makeup the headstock.
Hopefully you have the Owner's Manual for your Mark 5 but if not there is a PDF version available through the link below. It is the first topic on this section of the Forum. On the "My Google Drive" link there, Everett Davis has made available documents he has restored and there you can find the second edition of the Mark 5 Manual. That would be the edition that came with your Mark 5 originally. You do have to use a Google account to sign on with to access the documents but there is a wealth of information to be found there and is worth accessing it.
viewtopic.php?f=10&t=16113
There have been three different Saw Blade Guards made for the Mark 5/V's. The first was an option available early on for the Greenie Mark 5 and can only use up to the 9" blades that were the size that came for use with the early Mark 5. I do not recommend using that version of the Saw Blade Guard plus it is harder to find. Below is a picture of that Saw Blade Guard set.
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The second Saw Blade Guard is the one shown below.
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- 505627 Upper and 505628 Lower Saw Blade Guards - shoe.jpg (129.35 KiB) Viewed 1278 times
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It is Part Numbers 505627 and 505628 which is an easy to use and attach Saw Blade Guard Set for the Mark 5/V with no drilling or cutting needed. It is less popular because of the cast aluminum upper blade guard not allowing you to see the cut being made. If you do decide to go with this guard set do make sure it has the parts shown in the picture especially the part called the "shoe" which is the heavy wire loop shown circled in red in the picture above that lifts the upper guard up over the material being cut. Without it the upper guard is useless and this is the most common missing part I have seen on these for sale.
The Guard set in the picture in the previous post is the last Saw Blade Guard set that was made for the Mark V Model 500 with the two 2-1/2" dust collection ports upgrade. The has the clear plastic upper guard so you can see the cut being made. It is more work to put on and remove from the Mark 5/V. Installing it on your Mark 5 Greenie will take some drilling and cutting on the Table Tie Bar.
Remember we are always happy to help with any questions you may have.