Some tips (having built a good 25-30 computers from scratch in my lifetime):
- It's actually a good sign that the CPU and heatsink are bonded together. That means they're tight fitting
- Once you separate the CPU and heatsink, alcohol wipes are your best best for cleaning off ALL residue before re-seating the CPU and heatsink
- When reapplying thermal paste, you don't want it covering the CPU like honey. It is ONLY supposed to cover the tiny imperfections on the metal (even though it seems perfectly smooth). Therefore, you want to apply a TINY amount and then use an old credit card to smooth it over the entire surface. You should be able to see any text or markings on the back of the CPU THROUGH the thermal paste. If you can't see any of the metal under the thermal paste, you used WAY too much!
- Bent CPU pins can be fixed fairly easily using a small pair of needle-nosed pliers. I've bent a few pins in my days and you can straighten them out quite well but inserting the pliers vertically and rotating them around the pin then pinching to straighten it out from all angles.
- If you're trying to re-insert the CPU, make sure you open the lever that allows you to re-seat the CPU, otherwise you're trying to jam the CPU into holes that are not aligned (in which case you'll probably bend the pins, see tip above)
If you have any other questions, don't hesitate to ask!