HTC Hero :: Speaker Crackle - Caused By Sim Card Holder Rattle?

Firstly just wanted to say how useful this forum has been in keeping up to date with all the latest goings on for my HTC Hero (well, T-Mobile G2 in my case). Anyway. I'm having some problems with the speaker on my phone, the one you hold to your ear, rather than the one that plays music, loud speaker etc. I think I've found a solution, so wanted to share that with you guys, but also find out if anyone else has had a similar problem.

My phone has started crackling a lot when making calls. Other people can hear me fine, but their voice seems to crackle and fizz if it gets too loud. If I turn the volume up on my phone it gets even worse. At first I thought it was a blown speaker or something, but looking at the sim card holder, it seems to be that that's causing a rattle, it gets vibrated when the sound comes through the speaker. When I tap the back of my phone, gently!, it makes a slight rattling sound. I can eliminate the problem entirely by taking the back off the phone and firmly holding the top of the battery, thus stopping the sim card holder rattling around. However this isn't an ideal solution for everyday use!