S2 rear brake trouble

[spanner rash]

Hello all, having some difficulty getting my rear brake working effectively...
I recently had to change the rear hub on my Li S2 due to shearing a couple of studs so I got the remade Scootopia S2 one, however since then the brake performance has drastically dropped- I used to be able to lock the rear wheel and skid but now I've had to really wind the adjuster in to get the brake to work at all. The trouble is sometimes it doesn't disengage when the pedal is released and drags for a bit. I've made sure the shoes are free on the pivot pins and the cam is greased and moving freely and the return spring is good. There's about 5mm left on the brake linings.
It seems to me that the cam is almost getting to the point of no return/maximum opening so was wondering if it's just simply time to get new shoes with more meat on them or whether there is a way to shim between the cam/shoes to make up for the difference between the hubs?
Appreciate any thoughts, cheers.

[CHRIS in MARGATE]

Cam over travelling so time for new shoes.
LI not GP

[spanner rash]

Cheers Chris, will try another set.
What puzzled me a bit was that the new hub needed the cable tightening up so much to get a pedal compared to the ancient one..

[Norfolk]

Sounds to me a case of the new brake drum has a larger internal diameter than your original, there only needs to be a slight difference to make a difference, if you get what I mean. If possible use an internal micrometer to measure the difference, if a micrometer is not available use a piece of wood nearly the correct diameter then use feeler gauges to assess the final measurements.