Transmission jumps from 1st to 2nd?

[JSMexUsa]

Hi guys,
I paid a shop to rebuild my transmission a couple years ago with 2 years warranty which expired a few months ago.

Now the transmission feels like switching hard from 1st to 2nd gear.

What can it be?

I hope is not a bad transmission again.

Will go back to the shop to have them checked hopping is a small issue.

Any ideas what can it be?

[oni_cb7]

I am guessing it is an automatic...

When was the last time the transmission fluid was changed?

[JSMexUsa]

Yes, it is automatic.

Transmission fluid was replace around a year ago when an axle was replaced like 12K ago.

I will change again and see what happens, that will be the cheapest and is better to check all the possible fixes before going to the shop where then can ripp me off and tell me needs another $1500 rebuild.

Any other ideas?

[Fleetw00d]

How much of the fluid did you change? A single drain and fill only replaces about 40% of the fluid (2.5 out of 6 quarts).

[JSMexUsa]

I replaced 3 qts. once every 15K