Long summarization

Hello I was trying to use the t5 to summarize text that’s around 10,000 characters, and return about 20% of the original length. However it seems to only do about 1 sentences and the rest is either blank spaces or random words depending on what the no_repeat_ngram_size is set too. Also if I set num_return_sequences to something more then 1, it will return “and…” as a sequence.

Should I be using a different model?