From the facts you've posted, you've given adequate notice. Your tenant cannot deny you the right to make repairs to protect the dwelling -- especially if those repairs don't involve going inside the leased premises.
DISCLAIMER: Brandy A. Peeples is licensed to practice law in the State of Maryland. This answer is being provided for informational purposes only and the laws of your jurisdiction may differ. This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. Under no circumstances does this answer constitute the establishment of an attorney-client relationship. For legal advice relating to your specific situation, I strongly urge you to consult with an attorney in your area. NO COMMUNICATIONS WITH ME ARE TO BE CONSTRUED AS ARISING FROM AN ATTORNEY-CLIENT RELATIONSHIP AND NO ATTORNEY-CLIENT RELATIONSHIP WILL BE ESTABLISHED WITH ME UNLESS I HAVE EXPRESSLY AGREED TO UNDERTAKE YOUR REPRESENTATION, WHICH INCLUDES THE EXECUTION OF A WRITTEN AGREEMENT OF RETAINER.
I do not see any reason why you would not be able to clean the gutters. This is an outdoor repair and if you do not repair this, it could likely do more damage to the inside of the home as well as tenant's belongings. You have followed proper procedure and given 24 hours notice (36 hours, actually), and you are well within your rights to repair the gutters.
***Answering legal questions is a complex matter and cannot be done without further research. My answer here is based solely on the information given in the question and should be taken as informational only. This is not legal advice. My answer here does not indicate that I represent you now, or that I will represent you at a later time. I take clients on a case-by-case basis, and only after initial consultations. ***