Pin on wheel loader bucket wont take grease

Hello all

I have a 1.7m3 (3 tonne) bucket on my 10t wheel loader and one of the pins to the bucket will not take grease.

I have tried the following
1) cleaning the inside by taking of the grease nipple, washing it with solvent and connecting air and pressurising to 1000kPa - to try and blow it through
2) heating it up with a heat gun when trying 3 and 4 below
3) undoing the bolts to the pin back and using a 10t ram to push it out - it would not budge
4) trying to knock the pin out with a sledge hammer
5) wiggling the bucket whilst trying to pump in grease

I assume that dirt has got in and blocked the grease path so I thought that blowing it out would be an idea, then I thought take out the pin and clean it.....

Any ideas?

cheers