Locke Well & Pump Company

My ST 1072 AO Smith inground pool pump MOTOR (56J; 1081 design; 7.3 A; 1.5 SF) (Hayward Super Pump) is having big issues. I found in my initial search that replacing it with a more energy efficient model would be way more cost-effective long-term than fixing the old with parts. What I don't fully understand is which model to go for.
Both of these are rated for extra energy efficiency:
CT1072 5.5 A, 1.5 SF $217
UCT1072 4.0A, 1.0 SF $143
physical characteristics look like they would fit my pump. With the price difference and the lower A draw, I'd go for the UCT1072. Is the service factor that important? Elec Engr at work says that the more efficient models have a lower service factor by nature of design. Love to get the savings from a 4A pump over a 7.3 A.
My pool is 18 x 36 with drain in deep end and skimmer on side; pump house is 8 ft from shallow end. pump through salt chlorinator cell. (which has oversized diameter to minimize restrictions)
so, are either of these acceptable to replace mine? and any perceived issues going with the UCT1072 to maximise savings?
Thanks!

Please reply with with the manufacturer and model of the pump you have. This way I can research the original motor and determine which model motor will work best. The service factor on pool pumps are critical in choosing a replacement motor, therefore, the UTC model may not work because of its low service factor.

Sorry, didn't see the man and model in your post. Is it a Super Pump or Super Pump II? Also, if you can give me the actual model, that would be best.

Quite frankly, I would not recommend the UCT1072 because of the service factor. If you went with the UCT1102, which would be 1HP, then you are at the same amperage as the CT1072. Most of the time, pool manufacturers will play with the service factor of a given motor to determine if they can utilize a larger impeller for performance. If the ST1072 was not overloading and was working fine, I would go with the CT1072 and not take a chance on the 1.0 service factor of the UCT1072.

okay, thanks for the recommendation. I'll go with the CT series for better eff with the same sf and hp.

Seems like a 2-speed option would save even more elec, by running the pump slow for long periods for the salt chlorinator, and just use the high (normal) speed for vacuuming. But apparently they're not avail in 3/4; and going to 1 hp and trying to get the hp x sf to line up and etc doesn't look like it will work out. I like to make things better, but you have to stop somewhere...

finally got details on the pump
housing : 2605 XL EC1309 enclosure 3
diffuser: looks like SP-2600-8, but a parts diagram found online has -13 instead of 8. maybe hard to read the plastic marks.
impeller: SP2605-C

if the pump had a ST1072 and was working good and lasted a good while, then, I would recommend the CT1072