Hi Chris,
It does sound like a solder joint issue, especially with the temperature sensitivity you've noticed. When it comes to re-soldering, you may want to pay particular attention to the joints that seem to be affected by temperature changes. However, it's important to exercise caution and ensure proper soldering techniques to avoid any damage.
On a different note, I hope this information is a helpful
birthday gift for you, and I wish you success in resolving your speedometer issue!
Best regards,
Sofia