Hi everyone, I am new to the group and after some support with my Aprilia Area 51

I know there are not many Aprilia Area 51 's around now, so I am hoping someone may be able to help me out on a couple of issues that I have.
I purchased the bike for my son a couple of years ago when he turned 16, He has ridden the bike daily and only had one major problem with it (rollers breaking up, so I replaced these and a new belt).
The bike has been stood up for a few months now, after him passing his car test, so I thought I would get it back on the road again to either sell or use myself.
Unfortunately, the front brake has stopped working... I replaced the calliper seals and bled the system, but still get no pressure when the lever is applied. If you pump the lever a few times, the piston does come out , but when you let go, the pistons retract all the way back in. I clamped the brake hose, and the lever is a lot better. It had happened once before, but gradually got better. Just wondering if anyone has had the same issue?
Secondly, although my son used it and managed with it, it is not very good up hills (to the extent that he had to turn round at one point and go a different way!)... it is great on the flat (55mph), but as soon as it sees the hill it slows. When I replaced the rollers, I fitted 5 gram ones as was fitted originally, could someone advise me what to do or fit please?
Thanks in advance.
Kevin