Quill stem adaptor help

[thiscocks]

Hi. I think this is the correct area on the forum- if not please move!
I have just got an aluminium Bianchi with a threaded steerer and an ITM quill stem adaptor for an 1.1/8" ITM stem. I assumed it would be a simple undo bolt and whack job but what I thought was a cap covering a bolt appears to be solid aluminium! I got a screwdriver on it to try and prise it up but nothing happened so I started trying to chisel it off but it started breaking away as if it was the same aluminium material as the rest of the adaptor...I tried twisting the main cap with mole grips and hitting it from underneath too- but no, seems all rock solid I thought I'd ask here before I start attacking it further: has anyone seen an adaptor like this and know how to get the bloody thing off!?

 

[novocaine]

your aluminium is just a cap, you need to pry it out. personally I'd drill a hole in it and then pop it off. they were a bitch to get out.

 

[thiscocks]

Ah explains it. I assume its been on there for years then and has basically welded its self in!