Bro sky kid...
just sharing...
normally manual gb there is alot of linkage joint just above the gb where the gear lever seat...
either 1st up 2nd down then flick to right for 3rd up 4th down and last the 5th also for reverse gear...
all this connection normally there is bush and pins...
so may be all the bush are loose or ever broken...
so do some inspection to all this moving parts...
After inspection found out this bush and pins are in good condition...
then move on to the clutch servo pump check for any leaking...
then the clutch plate wear and tear...
all ok may be the synchronizer inside...
p/s also happened during reversing???
when is the last Gb fluid change???
my 3 cents...may be wrong...