radarsfriend

Just to add to jrtrebor's comment. There will be wear in the first connection under the shifter where it makes the first connection to the rod that goes down to the frame area. Look closely at that connection for a rounded out condition.  If it is worn, and you plan to keep the machine just replace that connection;  either the shifter and or the rod going down.

I have had a similar issue with my drive wheels.  I have a fairly new less than 20 hour use old Ariens deluxe 28 inch. The cable that operates the release mech was slightly to loose so I tightened slightly and with the machine running I wiggled the lever up and down and had posi drive again. I don't use that function very much but it works better than when machine was new.

I see that you have somewhat of a dilema because you do have  limited storage space.  I have a similar driveway as yours that is shared with the house next door.  I have to be able to park behind my house or inside the garage in the winter months.  The first few years in the house I shoveled which became to labor intensive. I bought a used MTD and refurbished it. Had it 5 years but the 26 inch 8 hp setup was $#%*bersome to steer and the shute operation required extra labor. I bought the Ariens deluxe 28 inch with the USA made Briggs 250 cc motor.  This machine works well for me as I'm able to lay waste to heavy snow and send to another area. No one in my area has a blower that blows the snow as far as this machine.  There is a reason why Ariens has the patent on a two belt impeller drive. There is also a reason why Ariens uses a 14 inch impellar instead of a 12 inch. I paid $1050.00 for my machine which included delivery and setup. It has been worth every nickel.