As last resorts, you make try making up a hydraulic hose that will screw in where the grease nipple is and putting hydraulic pressure from the loaders couplers to it.
Also before cutting the quick attach appart could it be removed and set up in a press to push the pin up? It is surprizing the differece between hammering which tends to mushroom the pin and what a even 50 tons of force can do.
Ken
Update...
The pin is out, but it didn't really survive the incident unscathed.
First I had to cut an inch off the end of the pin. (I saved the slug). This enabled me to get the bucket off.
Next I used a torch and heated the collar the pin slides thru to cherry red. Once heated I went for the 10 Lb. sledge but no joy trying to drive the pin in. I then removed all the linkages along with the other pin (left side as you face the loader). This gave me a clear channel thru the Quick Latch and access to the back of the stuck pin. I then inserted a 1/2" steel pipe thru the left pin channel all the way to the back of the stuck pin. After heating the collar to cherry again I drove the stuck pin from behind, which of course completely destroyed the two welded tabs on the back of the pin where it attached to the linkage but at this point I didn't really care... I just wanted that pin out.
After repeated heavy blows with the sledge, the pin moved out about 1/2" . I soaked as much of the pin as I could with PB Buster and then drove the pin back in from the now blunt end (where I cut it off) of the pin. I continued knocking the pin in and out this way and finally... out it came.
Now into the shop for some welding. I ground a "V" groove in the cut-off end of the pin and the slug and welded the slug back onto the pin and ground it smooth. I then cut two new tabs from 1/8" x 3/4" flat steel stock and welded them to the backside of the pin. Over to the drill press for some holes in the tabs and wadaya know... a new (repaired) locking pin.
All new hardware... the lock nuts and bolts used to connect the linkages... and the Quick Tach is back in action. I love it when a plan comes together.