Find the correct sized socket that fits inside,then dust off the dremel and cut out where it goes round the retaining pin,bit better than a broom handle!!
HW35 is a fiddle Davy,undo the rear pin on the trigger,holding the safety at the same time.
Once removed drift out the front pin and remove the trigger.
Get a big spanner wrap it in cloth,put it in the trigger housing an tap sharply with a hammer.
If the original springs in,put the rear of the cylinder on a cloth on the floor,stand over it gripping firmly and unwind it slowly,towards the end.
Job done!
Make sure you cock the trig