Problems with Air Source Heat Pump

[Bigfreeze]

Hi ,
Ive a recent problem with Air Source Heat Pump in Heat Mode.
With Outside Air Temp at 1deg C the Outdoor unit pipework at the Outdoor Unit measures 58degC & 18 Deg C. and at the Input of the Indoor Unit the Pipework its 55 & 20 Deg C.
However I must of knocked the pipework a few weeks back & had a very slight leak on one of the fittings... I've nipped this up & checked everything tight with soapy water.. However temperatures inside are struggling to get above 20 degC & noticed that the outside evaporator only ices up at the bottom 1/3 & no higher( however i don't know if this is normal)... Would this be due to loss of coolant because pipe temperatures do seem pretty good I would think.. At 6dec C outside air temp yesterday the pipes at the Outdoor unit in Heat mode where 64deg C & 21Deg C respectively measured with a digital thermocouple.. Any help would be appreciated

Thats some serious DT's you're getting there. Where are you taking your measurements?
Is this an air to water unit?
What type of heat distribution system have you?