What weight oil are you using? How many miles? I always used 10w30 in mine when I had it with around 100k on it and never had an issue with oil pressure. Also, does the tick disappear when you get oil pressure, if not then are you sure its not an exhaust tick? Mine had a broken exhaust stud and it had a tick that sounded like a lifter. One thing to try to bring up oil pressure (I assume the pressure used to be higher and that you have not changed weights), 500 miles before you change the oil add some seafoam to it. The other way to clean your motor well would be to change the oil and replace one quart with atf then change the oil again after about 1000 miles. Either way will clean the inside of your motor really well in case you have any kind of sludge issues or debris in the pan that could be clogging up the pickup screen. Otherwise, your pump may be worn.