I have worked on a few of these little reels. They are very reliable for what they cost and go on forever.
I have just brought one and wondered what could be done to improve it.
First obvious thing to do is upgrade the clutch with carbontex washers. Considering the age of these reels
the original washers are most likely towards the end of their life so a carbontex set is a no brainer.
Second thought is what could I do to make it smoother. After all it only has brass bushings. When I stripped the reel I put the bearings to one side so I could measure them to see if I could replace them with ball bearings.
Hey presto, yes you can and it aint very expensive. You need 2 size bearings
For the large bush you need a 7 x 14 x 3.5mm bearing (inside x outside x width)
For the small bush you will need a 4 x 11 x 4mm bearing
As for the clutch washers you need a set for one of the following reels which are the same as the SL175H
30H, 47H, SMF170.
The kit also includes the smaller washer under the main gear.
Some anglers might also prefer a longer power handle. Off hand I cant remember what other reels have the same size reel fitting. It is an oval hole though.
Bearing conversion works great. the reel feels so much smoother and the clutch is more smoother and powerful.