The roller/spring is not really a wear item. I'd suspect there is simply a fair amount of wear and slop in your shift linkage making it loose and giving it inertia as you select gears.
Fiddling is not likely to correct the shift issues there is a very specific clearance on the shift tube and that is the first adjustment. Like I said read the adjustments and check them. Don't assume you can gloss over the steps and expect it to work like new.
Besides is a free download.`
http://67-72chevytrucks.com/vboard/s...d.php?t=558016