Garage opener - replacement advice wanted
I have a 15yr old Liftmaster 1/2HP chain drive opener that recently broke. The plastic gear has stripped out and I could just replace the part ($5-$6 or so). However, I previously (3 years ago) had to increase the "strength" of the lift with the adjustment screws on the opener. I keep the rollers and track lubricated so I'm wondering if it was a poor install on the door (runs OK in summer, locks up in winter due to temp changes). It's also a cheap, noisy unit. So, keeping in mind the unit's age, which of the following options do you all recommend? -->
1) Just replace the gear and re-lube everything. It should last another 10 years or so...
2) Replace the gear & worm drive & re-lube everything. (worm gear is not broken but since I'm in there...)
3) Replace gears and all the rollers. Which roller style and brand is recommended (nylon, steel, ???)?
4) Replace the entire lift unit & rollers. Make any track adjustments if required. What's recommended for 1/2HP lifts? My door is ~24' wide and fiberglass (not heavy). It looks like Chamberlain Wisperdrive is the best option (even though all the residential stuff is cheap)?
5) Replace everything (opener, door, door rails, etc.). Asked another way: If the door panels are OK, do the metal rails ever wear out?