You have to clean out the bush hole loads more than you think you need to.
I use a rotary flap thing and don't stop until it's all shiney. Grease the bush and hole and then wind it in with stud bar / thick washers.
Do not hit it with a hammer cos it will mushroom and never go in.
Horrible job
Assume you mean the bushes in the actual chassis for the above.
It is the bush in the chassis itself yes...bloody pig awful job but got there eventually ....took so bloody long though so bit behind with today's timetable now.
If they have been in for a long time the hole gets ovaled. Suggest you ream them well first. I recall it's a 28 or 32 mm reamer. I did this after similar problem and they drifted in ok afterwards with not too much effort...and plenty copper grease.