Right.
I have a wanderer that looks much like Rod's minus mitres.
I did managed to adjust it, it's not complete, but now it is cutting fairly straigh.
1) My saw does to have a cant adjustment for idler wheel, it is a little angles and back from driver wheel. Driver wheel was a little loose. It has key/stop screw and retaing ring.
2) I adjusted quide that supports the blade from the back, until they lined up with wheels.
3) Then I checked that the part support is lined up with pivot shaft and blade is lined up square to them.
4) Spent some time trying to adjust guide rollers straight to the table. Pretty hopeless with a ruler or such nipped between rollers. I assumed that the guide roll holder milled surfaces are square and I put try square on top of it and another resting on the table. It was pretty easy to sight them and adjust guides straigh then.
Now it cuts pretty straight.
But quide rollers (ball bearings) are worn, and ideler wheel bushing/shaft is worn. These parts will need attention eventtually.
Pekka