Hi Pkayen,
As you say the leaves of the top of the plant have red spots on, is it possible that they have had a cold wind or cold draught going over them lately, especially in the night? Red spots on leaves can be caused by a sudden drop in temperature. If this is the cause, don't worry, at worst they will die and fall off but new ones will grow in there place - Kath:)

Thank you, Kath. The temps have fluctuated quite a bit in the last few weeks, between hot and mild. I think I shall wait and see.

The red spots are still there. I also found some sticky stuff on the underside of the leaves. New growth is restricted to the lower parts of the plant. It has been scant, but looks ok. Should I prune the affected old parts (there is little or no new shoots in these)? I have never pruned it since I planted it over a year ago. What can I do to encourage growth?

Yes prune it back to the new growth Pkayen, then remove any old leaves etc that are laying on the soil. Then I would give it a spray (not when the sun is shining on the plant), with an insecticide, as it's sticky, sounds as if you have had a bug/insect of some sort - Kath:)

Thank you, Kath. I'll let you know how it goes.