Palio will not shift into reverse

Hi All,
I have a 1998 Palio with 1.0 liter gasoline engine. It has a 5 speed manual transmission. Recently I have had trouble shifting into 5th gear. It will go but it requires a considerable shove to the right and up to get into 5th. There are no odd noises or grinding sounds. Just stiff. Yesteray I discovered I can no longer shift into reverse. The reverse lockout slides up as usual but I cannot get into the reverse gear. I slid up the shifter boot and discovered a white plastic piece that covers a horizontal bar just in front of the shift lever is broken. Im not sure what its function is. The white plastic piece which surrounds the base of the shifter appears to be OK. Does this sound like a linkage adjustment problem and is it at the point where the shifter enters the base or somewhere closer to the engine? Does anyone have a .PDF schematic of the shifter linkage?
Thanks,
Kenno

This is a common problem, I don't think the parts you mention are the reason.
On top of your gearbox is the shift system, cable operated.
There is a long bolt that will rust, and cause the problems you have.
Take it apart, lubricate it, and you will be fine.

I also have difficulties in shifting to reverse. I push the pedal, then try to shift, while trying I leave the pedal a bit, then it shifts the rear gear.

When ı have difficulties in shifting to first gear, I first shift to two, then immediately one and it is done.

Weird transmission huh

Your cables are in need of adjustment...

I had reverse select problem on inspection the " plastic " molding at the bottom of the shift stick was cracked and rose up when reverse was selected
Cured with a piece of aluminium flat bar and a large self tapping screw to hold front of moulding down ( cost price of part at Fiat SAR 425.00 ) been working fine for 18 mths now