The best I could do is not good:

1. An exploded view at the address below.
2. An attachment you should be able to copy and enlarge.
3. I Bet! If someone could send a pic of the switch in place you would remember.
4. Send a pic with it as close as you can remember and we might be able to help.
5. These can be challenging and we forget to take pics before and during disassembly.

http://www.ereplacementparts.com/poulan-ght220-type-gas-hedge-trimmer-parts-c-16962_31739_31745.html

Here is a link that might be useful: Poulan Excalibur GHT Model 220 Diagram