Vokera compact 28 hot water isn't fluctuating cold and hot

[Inverness]

went to see about a problem. I've never dealt with these kind of boilers. I'm new to it so be gentle..
Any advice what the issue could be? Blocked flow ?

 

[AMGasServices]

Check the flexible flow and return pipes they may be full of muck.

How long would you say it stays on for ?

 

[Darren Jackson]

De-scale the rolled lead hex, swap out the 2 thermistors & the high limt stat, clean the flow restrictor. And set the HW litre per min throttle to Mi's. Then reset the max & min gas rates to factory settings.