Have a look and see if there is any tape in the channel. There "should be". Heat up the outside with a hair dryer and slowly pull the channel away from the glass. You might find three pieces of self adhesive felt. It is really easy to heat up the adhesive.

  no tape to be seen and no adhesive at all 

I dont have a mallet, should i tempt fate and use a normal hammer with padding between hammer and trim?? Lots of rags for example?