Agreed, I would definately not use a resistor which has been dislodged in such a way, as the ceramic body of the resistor can develop hairline cracks making the resistor open circuit permanently or intermittently, causing future headaches.
Any place that does SMD work should have them, take along a chocolate bar or something as payment, the resistors cost less than 3ยข each. Staff would not want to make an invoice for a few cents, they'd loose money, but they'd be overjoyed at the prospect of free chocolate!
Take along the original parts as there are various SMD resistor sizes, though if they're from an Amiga motherboard, they'll be 1206 size. The smaller but more common 0805 size resistors will still fit OK.
If you have spare motherboards for parts, locate resistors with the same value and use them as replacements.
Look at the board schematic and see if they're really necessary. Designers somethings do funny things like add pull up/down resistors on a TTL driven output and other such pointless things.
When you fit the new device, do not use any glue, as many types contain cyanoacrilate, and if you heat this (when soldering the ends) gives off extremely dangerous hydrogen cyanide fumes!
Use solder wick to remove all the old solder, hold the new SMD part in place with tweesers, and solder either end. Simple.
