Mira 915ba

The Mira 915 B shower valve spares can be found in this link provided to our website- www.showerdoc.com/mira-915-b-shower-spares

From what you are saying this shower definitely needs the flow cartridge stripped, serviced with new seals and everything lubricated.

The cartridges are basically the most expensive way of repairing your shower, however it's the easiest - The temp cart 412.01 and flow cart - 902.85 can both be found on the spares list in the link above. However ...Your shower will no doubt only need the cartridge or cartridges servicing with these seal kits

Temp Kit - 935.01 - www.showerdoc.com/mira-service-pack-temp-915-comp-b-935-01

Flow Kit - 935.02 - www.showerdoc.com/mira-service-pack-915-flow-kit-935-02

Stripping the cartridge or cartridges down and replacing all the seals, lubricating all moving parts / seals etc will sort most issue with the shower like the following:
Shower stiff to operate
Shower ripping when switched off
Shower fluctuating hot & cold
Shower leaking through the font of the cartridge.
Temperature issues.

When servicing a cartridge on this shower , Mira do suggest servicing both at the same time whilst you have the shower water off and the it half stripped down anyway...basically killing two birds with one stone and this saves you doing it twice in the future.

Regards